fix: use local path deps for redox_syscall

Semver pre-release suffix (-rb0.2.5) breaks Cargo's [patch.crates-io]
matching for transitive deps. Build metadata (+rb0.2.5) is semver-
compatible: ^0.9.0 matches 0.9.0+rb0.2.5, patch redirection works,
and the Red Bear suffix is still visible in the version string.

.gitignore

@@ -0,0 +1,2 @@
+/build
+/target

.gitlab-ci.yml

@@ -0,0 +1,35 @@
+image: "redoxos/redoxer:latest"
+
+before_script:
+  - apt-get install nasm
+  - rustup component add rust-src
+
+stages:
+  - host
+
+build:i686:
+  stage: host
+  script:
+    - mkdir -p target/i686
+    - cd target/i686
+    - TARGET=x86-unknown-none make -f ${CI_PROJECT_DIR}/Makefile -C `pwd` `pwd`/bootloader.bin `pwd`/bootloader-live.bin
+
+build:x86_64:
+  stage: host
+  script:
+    - mkdir -p target/x86_64
+    - cd target/x86_64
+    - TARGET=x86_64-unknown-uefi make -f ${CI_PROJECT_DIR}/Makefile -C `pwd` `pwd`/bootloader.efi `pwd`/bootloader-live.efi
+
+build:aarch64:
+  stage: host
+  script:
+    - mkdir -p target/aarch64
+    - cd target/aarch64
+    - TARGET=aarch64-unknown-uefi make -f ${CI_PROJECT_DIR}/Makefile -C `pwd` `pwd`/bootloader.efi `pwd`/bootloader-live.efi
+
+fmt:
+  stage: host
+  script:
+      - rustup component add rustfmt-preview
+      - cargo fmt -- --check

.helix/config.toml

@@ -0,0 +1,2 @@
+[editor]
+auto-format = false

.helix/languages.toml

@@ -0,0 +1,5 @@
+[[language]]
+name = "rust"
+# TODO: Add more targets (BIOS, x86_32)
+# Uncomment this line and set cargo.target to your target to get accurate completions
+# config = { cargo.target = "aarch64-unknown-uefi", check.targets = ["x86_64-unknown-uefi", "aarch64-unknown-uefi"] }

Cargo.toml

@@ -0,0 +1,56 @@
+[package]
+name = "redox_bootloader"
+version = "1.0.0+rb0.2.5"
+authors = ["Jeremy Soller <jackpot51@gmail.com>", "vasilito <adminpupkin@gmail.com>"]
+edition = "2024"
+
+# UEFI uses bin target
+[[bin]]
+name = "bootloader"
+path = "src/main.rs"
+
+# BIOS uses lib target
+[lib]
+name = "bootloader"
+path = "src/main.rs"
+crate-type = ["staticlib"]
+
+[dependencies]
+bitflags = "1.3.2"
+linked_list_allocator = "0.10.5"
+log = "0.4.17"
+redox_syscall = { path = "../syscall" }
+spin = "0.9.5"
+
+[dependencies.redoxfs]
+version = "0.8"
+default-features = false
+features = ["log"]
+
+[target.'cfg(target_os = "uefi")'.dependencies]
+redox_uefi = { git = "https://gitlab.redox-os.org/redox-os/uefi.git" }
+redox_uefi_std = { git = "https://gitlab.redox-os.org/redox-os/uefi.git" }
+
+#TODO: riscv cannot use target_os = "uefi" at this time
+[target.'cfg(target_arch = "riscv64")'.dependencies]
+redox_uefi = { git = "https://gitlab.redox-os.org/redox-os/uefi.git" }
+redox_uefi_std = { git = "https://gitlab.redox-os.org/redox-os/uefi.git" }
+
+[target."aarch64-unknown-uefi".dependencies]
+dmidecode = "0.8.0"
+
+[target."x86_64-unknown-uefi".dependencies]
+x86 = "0.52.0"
+
+[target.'cfg(any(target_arch = "aarch64", target_arch = "riscv64"))'.dependencies]
+byteorder = { version = "1", default-features = false }
+fdt = { git = "https://github.com/repnop/fdt.git", rev = "2fb1409edd1877c714a0aa36b6a7c5351004be54" }
+
+[features]
+default = []
+live = []
+serial_debug = []
+
+
+[patch.crates-io]
+redox_syscall = { path = "../syscall" }

LICENSE

@@ -1,18 +1,21 @@
 MIT License
 
-Copyright (c) 2026 vasilito
+Copyright (c) 2017-2022 Redox OS
 
-Permission is hereby granted, free of charge, to any person obtaining a copy of this software and 
+Permission is hereby granted, free of charge, to any person obtaining a copy
-associated documentation files (the "Software"), to deal in the Software without restriction, including 
+of this software and associated documentation files (the "Software"), to deal
-without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 
+in the Software without restriction, including without limitation the rights
-copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the 
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
-following conditions:
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
 
-The above copyright notice and this permission notice shall be included in all copies or substantial 
+The above copyright notice and this permission notice shall be included in all
-portions of the Software.
+copies or substantial portions of the Software.
 
-THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT 
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
-LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO 
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
-EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER 
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
-IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE 
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
-USE OR OTHER DEALINGS IN THE SOFTWARE.
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

Makefile

@@ -0,0 +1,24 @@
+TARGET?=x86_64-unknown-uefi
+SOURCE:=$(dir $(realpath $(lastword $(MAKEFILE_LIST))))
+BUILD:=$(CURDIR)
+export RUST_TARGET_PATH?=$(SOURCE)/targets
+
+
+include $(SOURCE)/mk/$(TARGET).mk
+
+clean:
+	rm -rf build target
+
+$(BUILD)/filesystem:
+	mkdir -p $(BUILD)
+	rm -f $@.partial
+	mkdir $@.partial
+	fallocate -l 1MiB $@.partial/kernel
+	mv $@.partial $@
+
+$(BUILD)/filesystem.bin: $(BUILD)/filesystem
+	mkdir -p $(BUILD)
+	rm -f $@.partial
+	fallocate -l 254MiB $@.partial
+	redoxfs-ar $@.partial $<
+	mv $@.partial $@

README.md

@@ -1,3 +1,62 @@
-# RedBear-OS
+# Bootloader
 
-RedBear Operating System, based on RedoxOS. Licenced under MIT license.
+Redox OS Bootloader
+
+## Requirements
+
+These software needs to be available on the PATH at build time:
+
++ [mtools](https://www.gnu.org/software/mtools/)
++ [nasm](https://nasm.us/)
++ [redoxfs-ar](https://gitlab.redox-os.org/redox-os/redoxfs)
+
+## Building
+
+```sh
+make TARGET=<triplet> BUILD=build all
+```
+
+The `<triplet>` is one of:
+
+| ARCH | Boot Mode | Triplets |
+|---|---|---|
+| `i686` | BIOS | `x86-unknown-none` |
+| `x86_64` | BIOS | `x86-unknown-none` |
+| `x86_64` | UEFI | `x86_64-unknown-uefi` |
+| `aarch64` | UEFI | `aarch64-unknown-uefi` |
+| `riscv64gc` | UEFI | `riscv64gc-unknown-uefi` |
+
+See [mk directory](./mk) for more information of how the build is working.
+
+## Entry points
+
+Please read [Boot Process](https://doc.redox-os.org/book/boot-process.html) in the Redox OS Book for an introductory guide.
+
+In this source code, some interesting files for entry points are:
+
++ BIOS boot stages: [asm/x86-unknown-none/bootloader.asm](./asm/x86-unknown-none/bootloader.asm)
++ BIOS boot entry: `fn start` at [src/os/bios/mod.rs](./src/os/bios/mod.rs)
++ UEFI boot entry: `fn main` at [src/os/uefi/mod.rs](src/os/uefi/mod.rs)
++ Common boot process: `fn main` at [src/main.rs](src/main.rs)
++ UEFI kernel entry: `fn kernel_entry` in each arch:
+  - `x86_64`: [src/os/uefi/arch/x86_64.rs](src/os/uefi/arch/x86_64.rs)
+  - `aarch64`: [src/os/uefi/arch/aarch64.rs](src/os/uefi/arch/aarch64.rs)
+  - `riscv64gc`: [src/os/uefi/arch/riscv64/mod.rs](src/os/uefi/arch/riscv64/mod.rs)
+
+## Debugging
+
+### QEMU
+
+```sh
+make TARGET=<triplet> BUILD=build qemu
+```
+
+## How To Contribute
+
+To learn how to contribute to this system component you need to read the following document:
+
+- [CONTRIBUTING.md](https://gitlab.redox-os.org/redox-os/redox/-/blob/master/CONTRIBUTING.md)
+
+## Development
+
+To learn how to do development with this system component inside the Redox build system you need to read the [Build System](https://doc.redox-os.org/book/build-system-reference.html) and [Coding and Building](https://doc.redox-os.org/book/coding-and-building.html) pages.

asm/arm/start.s

@@ -0,0 +1,17 @@
+interrupt_vector_table:
+    b . @ Reset
+    b . 
+    b . @ SWI instruction
+    b . 
+    b .
+    b .
+    b .
+    b .
+
+.comm stack, 0x10000 @ Reserve 64k stack in the BSS
+_start:
+    .globl _start
+    ldr sp, =stack+0x10000 @ Set up the stack
+    bl kstart @ Jump to the main function
+1: 
+    b 1b @ Halt

asm/x86-unknown-none/bootloader.asm

@@ -0,0 +1,31 @@
+sectalign off
+
+; stage 1 is sector 0, loaded at 0x7C00
+%include "stage1.asm"
+
+; GPT area from sector 1 to 33, loaded at 0x7E00
+times (33*512) db 0
+
+; stage 2, loaded at 0xC000
+stage2:
+    %include "stage2.asm"
+    align 512, db 0
+stage2.end:
+
+; the maximum size of stage2 is 4 KiB
+times (4*1024)-($-stage2) db 0
+
+; ISO compatibility, uses up space until 0x12400
+%include "iso.asm"
+
+times 3072 db 0 ; Pad to 0x13000
+
+; stage3, loaded at 0x13000
+stage3:
+    %defstr STAGE3_STR %[STAGE3]
+    incbin STAGE3_STR
+    align 512, db 0
+.end:
+
+; the maximum size of the boot loader portion is 384 KiB
+times (384*1024)-($-$$) db 0

asm/x86-unknown-none/cpuid.asm

@@ -0,0 +1,176 @@
+SECTION .text
+USE16
+
+cpuid_required_features:
+    .edx equ cpuid_edx.fpu | cpuid_edx.pse | cpuid_edx.pge | cpuid_edx.fxsr
+    .ecx equ 0
+
+cpuid_check:
+    ; If bit 21 of EFLAGS can be changed, then CPUID is supported
+    pushfd                               ;Save EFLAGS
+    pushfd                               ;Store EFLAGS
+    xor dword [esp],0x00200000           ;Invert the ID bit in stored EFLAGS
+    popfd                                ;Load stored EFLAGS (with ID bit inverted)
+    pushfd                               ;Store EFLAGS again (ID bit may or may not be inverted)
+    pop eax                              ;eax = modified EFLAGS (ID bit may or may not be inverted)
+    xor eax,[esp]                        ;eax = whichever bits were changed
+    popfd                                ;Restore original EFLAGS
+    test eax,0x00200000                  ;eax = zero if ID bit can't be changed, else non-zero
+    jz .no_cpuid
+
+    mov eax, 1
+    cpuid
+
+    and edx, cpuid_required_features.edx
+    cmp edx, cpuid_required_features.edx
+    jne .error
+
+    and ecx, cpuid_required_features.ecx
+    cmp ecx, cpuid_required_features.ecx
+    jne .error
+
+    ret
+
+.no_cpuid:
+    mov si, .msg_cpuid
+    call print
+
+    mov si, .msg_line
+    call print
+
+    jmp .halt
+
+.error:
+    push ecx
+    push edx
+
+    mov si, .msg_features
+    call print
+
+    mov si, .msg_line
+    call print
+
+    mov si, .msg_edx
+    call print
+
+    pop ebx
+    push ebx
+    shr ebx, 16
+    call print_hex
+
+    pop ebx
+    call print_hex
+
+    mov si, .msg_must_contain
+    call print
+
+    mov ebx, cpuid_required_features.edx
+    shr ebx, 16
+    call print_hex
+
+    mov ebx, cpuid_required_features.edx
+    call print_hex
+
+    mov si, .msg_line
+    call print
+
+    mov si, .msg_ecx
+    call print
+
+    pop ebx
+    push ebx
+    shr ebx, 16
+    call print_hex
+
+    pop ebx
+    call print_hex
+
+    mov si, .msg_must_contain
+    call print
+
+    mov ebx, cpuid_required_features.ecx
+    shr ebx, 16
+    call print_hex
+
+    mov ebx, cpuid_required_features.ecx
+    call print_hex
+
+    mov si, .msg_line
+    call print
+
+.halt:
+    cli
+    hlt
+    jmp .halt
+
+.msg_cpuid: db "CPUID not supported",0
+.msg_features: db "Required CPU features are not present",0
+.msg_line: db 13,10,0
+.msg_edx: db "EDX ",0
+.msg_ecx: db "ECX ",0
+.msg_must_contain: db " must contain ",0
+
+cpuid_edx:
+    .fpu                 equ 1 << 0
+    .vme                 equ 1 << 1
+    .de                  equ 1 << 2
+    .pse                 equ 1 << 3
+    .tsc                 equ 1 << 4
+    .msr                 equ 1 << 5
+    .pae                 equ 1 << 6
+    .mce                 equ 1 << 7
+    .cx8                 equ 1 << 8
+    .apic                equ 1 << 9
+    .sep                 equ 1 << 11
+    .mtrr                equ 1 << 12
+    .pge                 equ 1 << 13
+    .mca                 equ 1 << 14
+    .cmov                equ 1 << 15
+    .pat                 equ 1 << 16
+    .pse_36              equ 1 << 17
+    .psn                 equ 1 << 18
+    .clfsh               equ 1 << 19
+    .ds                  equ 1 << 21
+    .acpi                equ 1 << 22
+    .mmx                 equ 1 << 23
+    .fxsr                equ 1 << 24
+    .sse                 equ 1 << 25
+    .sse2                equ 1 << 26
+    .ss                  equ 1 << 27
+    .htt                 equ 1 << 28
+    .tm                  equ 1 << 29
+    .ia64                equ 1 << 30
+    .pbe                 equ 1 << 31
+
+cpuid_ecx:
+    .sse3                equ 1 << 0
+    .pclmulqdq           equ 1 << 1
+    .dtes64              equ 1 << 2
+    .monitor             equ 1 << 3
+    .ds_cpl              equ 1 << 4
+    .vmx                 equ 1 << 5
+    .smx                 equ 1 << 6
+    .est                 equ 1 << 7
+    .tm2                 equ 1 << 8
+    .ssse3               equ 1 << 9
+    .cnxt_id             equ 1 << 10
+    .sdbg                equ 1 << 11
+    .fma                 equ 1 << 12
+    .cmpxchg16b          equ 1 << 13
+    .xtpr                equ 1 << 14
+    .pdcm                equ 1 << 15
+    .pcid                equ 1 << 17
+    .dca                 equ 1 << 18
+    .sse4_1              equ 1 << 19
+    .sse4_2              equ 1 << 20
+    .x2apic              equ 1 << 21
+    .movbe               equ 1 << 22
+    .popcnt              equ 1 << 23
+    .tsc_deadline        equ 1 << 24
+    .aes                 equ 1 << 25
+    .xsave               equ 1 << 26
+    .osxsave             equ 1 << 27
+    .avx                 equ 1 << 28
+    .f16c                equ 1 << 29
+    .rdrand              equ 1 << 30
+    .hypervisor          equ 1 << 31

asm/x86-unknown-none/gdt.asm

@@ -0,0 +1,128 @@
+SECTION .text ; cannot use .data
+
+struc GDTEntry
+    .limitl resw 1
+    .basel resw 1
+    .basem resb 1
+    .attribute resb 1
+    .flags__limith resb 1
+    .baseh resb 1
+endstruc
+
+gdt_attr:
+    .present              equ 1 << 7
+    .ring1                equ 1 << 5
+    .ring2                equ 1 << 6
+    .ring3                equ 1 << 5 | 1 << 6
+    .user                 equ 1 << 4
+;user
+    .code                 equ 1 << 3
+;   code
+    .conforming           equ 1 << 2
+    .readable             equ 1 << 1
+;   data
+    .expand_down          equ 1 << 2
+    .writable             equ 1 << 1
+    .accessed             equ 1 << 0
+;system
+;   legacy
+    .tssAvailabe16        equ 0x1
+    .ldt                  equ 0x2
+    .tssBusy16            equ 0x3
+    .call16               equ 0x4
+    .task                 equ 0x5
+    .interrupt16          equ 0x6
+    .trap16               equ 0x7
+    .tssAvailabe32        equ 0x9
+    .tssBusy32            equ 0xB
+    .call32               equ 0xC
+    .interrupt32          equ 0xE
+    .trap32               equ 0xF
+;   long mode
+    .ldt32                equ 0x2
+    .tssAvailabe64        equ 0x9
+    .tssBusy64            equ 0xB
+    .call64               equ 0xC
+    .interrupt64          equ 0xE
+    .trap64               equ 0xF
+
+gdt_flag:
+    .granularity equ 1 << 7
+    .available equ 1 << 4
+;user
+    .default_operand_size equ 1 << 6
+;   code
+    .long_mode equ 1 << 5
+;   data
+    .reserved equ 1 << 5
+
+gdtr:
+    dw gdt.end + 1  ; size
+    dq gdt          ; offset
+
+gdt:
+.null equ $ - gdt
+    dq 0
+
+.lm64_code equ $ - gdt
+istruc GDTEntry
+    at GDTEntry.limitl, dw 0
+    at GDTEntry.basel, dw 0
+    at GDTEntry.basem, db 0
+    at GDTEntry.attribute, db gdt_attr.present | gdt_attr.user | gdt_attr.code
+    at GDTEntry.flags__limith, db gdt_flag.long_mode
+    at GDTEntry.baseh, db 0
+iend
+
+.lm64_data equ $ - gdt
+istruc GDTEntry
+    at GDTEntry.limitl, dw 0
+    at GDTEntry.basel, dw 0
+    at GDTEntry.basem, db 0
+; AMD System Programming Manual states that the writeable bit is ignored in long mode, but ss can not be set to this descriptor without it
+    at GDTEntry.attribute, db gdt_attr.present | gdt_attr.user | gdt_attr.writable
+    at GDTEntry.flags__limith, db 0
+    at GDTEntry.baseh, db 0
+iend
+
+.pm32_code equ $ - gdt
+    istruc GDTEntry
+        at GDTEntry.limitl, dw 0xFFFF
+        at GDTEntry.basel, dw 0
+        at GDTEntry.basem, db 0
+        at GDTEntry.attribute, db gdt_attr.present | gdt_attr.user | gdt_attr.code | gdt_attr.readable
+        at GDTEntry.flags__limith, db 0xF | gdt_flag.granularity | gdt_flag.default_operand_size
+        at GDTEntry.baseh, db 0
+    iend
+
+.pm32_data equ $ - gdt
+    istruc GDTEntry
+        at GDTEntry.limitl, dw 0xFFFF
+        at GDTEntry.basel, dw 0
+        at GDTEntry.basem, db 0
+        at GDTEntry.attribute, db gdt_attr.present | gdt_attr.user | gdt_attr.writable
+        at GDTEntry.flags__limith, db 0xF | gdt_flag.granularity | gdt_flag.default_operand_size
+        at GDTEntry.baseh, db 0
+    iend
+
+.pm16_code equ $ - gdt
+    istruc GDTEntry
+        at GDTEntry.limitl, dw 0xFFFF
+        at GDTEntry.basel, dw 0
+        at GDTEntry.basem, db 0
+        at GDTEntry.attribute, db gdt_attr.present | gdt_attr.user | gdt_attr.code | gdt_attr.readable
+        at GDTEntry.flags__limith, db 0xF
+        at GDTEntry.baseh, db 0
+    iend
+
+.pm16_data equ $ - gdt
+    istruc GDTEntry
+        at GDTEntry.limitl, dw 0xFFFF
+        at GDTEntry.basel, dw 0
+        at GDTEntry.basem, db 0
+        at GDTEntry.attribute, db gdt_attr.present | gdt_attr.user | gdt_attr.writable
+        at GDTEntry.flags__limith, db 0xF
+        at GDTEntry.baseh, db 0
+    iend
+
+.end equ $ - gdt

asm/x86-unknown-none/iso.asm

@@ -0,0 +1,161 @@
+; Simple ISO emulation with el torito
+
+; Fill until CD sector 0x10
+times (0x10*2048)-($-$$) db 0
+
+; Volume record
+;TODO: fill in more fields
+iso_volume_record:
+db 1 ; Type volume record
+db "CD001" ; Identifier
+db 1 ; Version
+db 0 ; Unused
+times 32 db ' ' ; System identifier
+.volume_id: ; Volume identifier
+db 'Redox OS'
+times 32-($-.volume_id) db ' '
+times 8 db 0 ; Unused
+db 0x15, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x15 ; Volume space size (0x15)
+times 32 db 0 ; Unused
+db 0x01, 0x00, 0x00, 0x01 ; Volume set size
+db 0x01, 0x00, 0x00, 0x01 ; Volume sequence number
+db 0x00, 0x08, 0x08, 0x00 ; Logical block size in little and big endian
+
+times 156-($-iso_volume_record) db 0
+
+; Root directory entry
+.root_directory:
+db 0x22 ; Length of entry
+db 0x00 ; Length of extended attributes
+db 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x14 ; Location of extent (0x14)
+db 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00 ; Size of extent
+db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ; Recording time
+db 0x02 ; File flags
+db 0x00 ; Interleaved file unit size
+db 0x00 ; Interleaved gap size
+db 0x01, 0x00, 0x00, 0x01 ; Volume sequence number
+db 0x01 ; Length of file identifier
+db 0x00 ; File identifier
+
+times 128 db ' ' ; Volume set identifier
+times 128 db ' ' ; Publisher identifier
+times 128 db ' ' ; Data preparer identifier
+times 128 db ' ' ; Application identifier
+times 37 db ' ' ; Copyright file ID
+times 37 db ' ' ; Abstract file ID
+times 37 db ' ' ; Bibliographic file ID
+
+times 881-($-iso_volume_record) db 0
+
+db 1 ; File structure version
+
+; Fill until CD sector 0x11
+times (0x11*2048)-($-$$) db 0
+
+; Boot record
+iso_boot_record:
+db 0 ; Type boot record
+db "CD001" ; Identifier
+db 1 ; Version
+db "EL TORITO SPECIFICATION" ; Boot system identifier
+times 0x47-($ - iso_boot_record) db 0 ; Padding
+dd 0x13 ; Sector of boot catalog
+
+; Fill until CD sector 0x12
+times (0x12*2048)-($-$$) db 0
+
+; Terminator
+iso_terminator:
+db 0xFF ; Type terminator
+db "CD001" ; Identifier
+db 1 ; Version
+
+; Fill until CD sector 0x13
+times (0x13*2048)-($-$$) db 0
+
+; Boot catalog
+iso_boot_catalog:
+
+; Validation entry
+.validation:
+db 1 ; Header ID
+db 0 ; Platform ID (x86)
+dw 0 ; Reserved
+times 24 db 0 ; ID string
+dw 0x55aa ; Checksum
+dw 0xaa55 ; Key
+
+; Default entry
+.default:
+db 0x88 ; Bootable
+db 4 ; Hard drive emulation
+dw 0 ; Load segment (0 is platform default)
+db 0xEE ; Partition type (0xEE is protective MBR)
+db 0 ; Unused
+dw 1 ; Sector count
+dd 0 ; Start address for virtual disk
+times 20 db 0 ; Padding
+
+; EFI section header entry
+.efi_section_header:
+db 0x91 ; Final header
+db 0xEF ; Platform ID (EFI)
+dw 1 ; Number of section header entries
+times 28 db 0 ; ID string
+
+; EFI section entry
+.efi_section_entry:
+db 0x88 ; Bootable
+db 0 ; No emulation
+dw 0 ; Load segment (0 is platform default)
+db 0 ; Partition type (not used)
+db 0 ; Unused
+dw 512 ; Sector count (1 MiB = 512 CD sectors)
+dd 512 ; Start address for virtual disk (1 MiB = 512 CD sectors)
+times 20 db 0 ; Padding
+
+; Fill until CD sector 0x14
+times (0x14*2048)-($-$$) db 0
+
+iso_root_directory:
+.self:
+db 0x22 ; Length of entry
+db 0x00 ; Length of extended attributes
+db 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x14 ; Location of extent (0x14)
+db 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00 ; Size of extent
+db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ; Recording time
+db 0x02 ; File flags
+db 0x00 ; Interleaved file unit size
+db 0x00 ; Interleaved gap size
+db 0x01, 0x00, 0x00, 0x01 ; Volume sequence number
+db 0x01 ; Length of file identifier
+db 0x00 ; File identifier
+
+.parent:
+db 0x22 ; Length of entry
+db 0x00 ; Length of extended attributes
+db 0x14, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x14 ; Location of extent (0x14)
+db 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00 ; Size of extent
+db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ; Recording time
+db 0x02 ; File flags
+db 0x00 ; Interleaved file unit size
+db 0x00 ; Interleaved gap size
+db 0x01, 0x00, 0x00, 0x01 ; Volume sequence number
+db 0x01 ; Length of file identifier
+db 0x01 ; File identifier
+
+.boot_cat:
+db 0x2C ; Length of entry
+db 0x00 ; Length of extended attributes
+db 0x13, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x13 ; Location of extent (0x13)
+db 0x00, 0x08, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00 ; Size of extent
+db 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00 ; Recording time
+db 0x00 ; File flags
+db 0x00 ; Interleaved file unit size
+db 0x00 ; Interleaved gap size
+db 0x01, 0x00, 0x00, 0x01 ; Volume sequence number
+db 0x0A ; Length of file identifier
+db "BOOT.CAT;1",0 ; File identifier
+
+; Fill until CD sector 0x15
+times (0x15*2048)-($-$$) db 0

asm/x86-unknown-none/long_mode.asm

@@ -0,0 +1,56 @@
+SECTION .text
+USE32
+
+long_mode:
+.func: dq 0
+.page_table: dd 0
+
+.entry:
+    ; disable interrupts
+    cli
+
+    ; disable paging
+    mov eax, cr0
+    and eax, 0x7FFFFFFF
+    mov cr0, eax
+
+    ; enable FXSAVE/FXRSTOR, Page Global, Page Address Extension, and Page Size Extension
+    mov eax, cr4
+    or eax, 1 << 9 | 1 << 7 | 1 << 5 | 1 << 4
+    mov cr4, eax
+
+    ; load long mode GDT
+    lgdt [gdtr]
+
+    ; enable long mode
+    mov ecx, 0xC0000080               ; Read from the EFER MSR.
+    rdmsr
+    or eax, 1 << 11 | 1 << 8          ; Set the Long-Mode-Enable and NXE bit.
+    wrmsr
+
+    ; set page table
+    mov eax, [.page_table]
+    mov cr3, eax
+
+    ; enabling paging and protection simultaneously
+    mov eax, cr0
+    or eax, 1 << 31 | 1 << 16 | 1                ;Bit 31: Paging, Bit 16: write protect kernel, Bit 0: Protected Mode
+    mov cr0, eax
+
+    ; far jump to enable Long Mode and load CS with 64 bit segment
+    jmp gdt.lm64_code:.inner
+
+USE64
+
+.inner:
+    ; load all the other segments with 64 bit data segments
+    mov rax, gdt.lm64_data
+    mov ds, rax
+    mov es, rax
+    mov fs, rax
+    mov gs, rax
+    mov ss, rax
+
+    ; jump to specified function
+    mov rax, [.func]
+    jmp rax

asm/x86-unknown-none/print.asm

@@ -0,0 +1,67 @@
+SECTION .text
+USE16
+
+; provide function for printing in x86 real mode
+
+; print a string and a newline
+; CLOBBER
+;   ax
+print_line:
+    mov al, 13
+    call print_char
+    mov al, 10
+    jmp print_char
+
+; print a string
+; IN
+;   si: points at zero-terminated String
+; CLOBBER
+;   si, ax
+print:
+    pushf
+    cld
+.loop:
+    lodsb
+    test al, al
+    jz .done
+    call print_char
+    jmp .loop
+.done:
+    popf
+    ret
+
+; print a character
+; IN
+;   al: character to print
+print_char:
+    pusha
+    mov bx, 7
+    mov ah, 0x0e
+    int 0x10
+    popa
+    ret
+
+; print a number in hex
+; IN
+;   bx: the number
+; CLOBBER
+;   al, cx
+print_hex:
+    mov cx, 4
+.lp:
+    mov al, bh
+    shr al, 4
+
+    cmp al, 0xA
+    jb .below_0xA
+
+    add al, 'A' - 0xA - '0'
+.below_0xA:
+    add al, '0'
+
+    call print_char
+
+    shl bx, 4
+    loop .lp
+
+    ret

asm/x86-unknown-none/protected_mode.asm

@@ -0,0 +1,36 @@
+SECTION .text
+USE16
+
+protected_mode:
+
+.func: dd 0
+
+.entry:
+    ; disable interrupts
+    cli
+
+    ; load protected mode GDT
+    lgdt [gdtr]
+
+    ; set protected mode bit of cr0
+    mov eax, cr0
+    or eax, 1
+    mov cr0, eax
+
+    ; far jump to load CS with 32 bit segment
+    jmp gdt.pm32_code:.inner
+
+USE32
+
+.inner:
+    ; load all the other segments with 32 bit data segments
+    mov eax, gdt.pm32_data
+    mov ds, eax
+    mov es, eax
+    mov fs, eax
+    mov gs, eax
+    mov ss, eax
+
+    ; jump to specified function
+    mov eax, [.func]
+    jmp eax

asm/x86-unknown-none/stage1.asm

@@ -0,0 +1,222 @@
+ORG 0x7C00
+SECTION .text
+USE16
+
+stage1: ; dl comes with disk
+    ; initialize segment registers
+    xor ax, ax
+    mov ds, ax
+    mov es, ax
+    mov ss, ax
+
+    ; initialize stack
+    mov sp, 0x7C00
+
+    ; initialize CS
+    push ax
+    push word .set_cs
+    retf
+
+.set_cs:
+
+    ; save disk number
+    mov [disk], dl
+
+    mov si, stage_msg
+    call print
+    mov al, '1'
+    call print_char
+    call print_line
+
+    ; read CHS gemotry
+    ;  CL (bits 0-5) = maximum sector number
+    ;  CL (bits 6-7) = high bits of max cylinder number
+    ;  CH = low bits of maximum cylinder number
+    ;  DH = maximum head number
+    mov ah, 0x08
+    mov dl, [disk]
+    xor di, di
+    int 0x13
+    jc error ; carry flag set on error
+    mov bl, ch
+    mov bh, cl
+    shr bh, 6
+    mov [chs.c], bx
+    shr dx, 8
+    inc dx ; returns heads - 1
+    mov [chs.h], dx
+    and cl, 0x3f
+    mov [chs.s], cl
+
+    mov eax, (stage2 - stage1) / 512
+    mov bx, stage2
+    mov cx, (stage3.end - stage2) / 512
+    mov dx, 0
+    call load
+
+    mov si, stage_msg
+    call print
+    mov al, '2'
+    call print_char
+    call print_line
+
+    jmp stage2.entry
+
+; load some sectors from disk to a buffer in memory
+; buffer has to be below 1MiB
+; IN
+;   ax: start sector
+;   bx: offset of buffer
+;   cx: number of sectors (512 Bytes each)
+;   dx: segment of buffer
+; CLOBBER
+;   ax, bx, cx, dx, si
+; TODO rewrite to (eventually) move larger parts at once
+; if that is done increase buffer_size_sectors in startup-common to that (max 0x80000 - startup_end)
+load:
+    cmp cx, 127
+    jbe .good_size
+
+    pusha
+    mov cx, 127
+    call load
+    popa
+    add eax, 127
+    add dx, 127 * 512 / 16
+    sub cx, 127
+
+    jmp load
+.good_size:
+    mov [DAPACK.addr], eax
+    mov [DAPACK.buf], bx
+    mov [DAPACK.count], cx
+    mov [DAPACK.seg], dx
+
+    call print_dapack
+
+    cmp byte [chs.s], 0
+    jne .chs
+    ;INT 0x13 extended read does not work on CDROM!
+    mov dl, [disk]
+    mov si, DAPACK
+    mov ah, 0x42
+    int 0x13
+    jc error ; carry flag set on error
+    ret
+
+.chs:
+    ; calculate CHS
+    xor edx, edx
+    mov eax, [DAPACK.addr]
+    div dword [chs.s] ; divide by sectors
+    mov ecx, edx ; move sector remainder to ecx
+    xor edx, edx
+    div dword [chs.h] ; divide by heads
+    ; eax has cylinders, edx has heads, ecx has sectors
+
+    ; Sector cannot be greater than 63
+    inc ecx ; Sector is base 1
+    cmp ecx, 63
+    ja error_chs
+
+    ; Head cannot be greater than 255
+    cmp edx, 255
+    ja error_chs
+
+    ; Cylinder cannot be greater than 1023
+    cmp eax, 1023
+    ja error_chs
+
+    ; Move CHS values to parameters
+    mov ch, al
+    shl ah, 6
+    and cl, 0x3f
+    or cl, ah
+    shl dx, 8
+
+    ; read from disk using CHS
+    mov al, [DAPACK.count]
+    mov ah, 0x02 ; disk read (CHS)
+    mov bx, [DAPACK.buf]
+    mov dl, [disk]
+    push es ; save ES
+    mov es, [DAPACK.seg]
+    int 0x13
+    pop es ; restore EC
+    jc error ; carry flag set on error
+    ret
+
+print_dapack:
+    mov bx, [DAPACK.addr + 2]
+    call print_hex
+
+    mov bx, [DAPACK.addr]
+    call print_hex
+
+    mov al, '#'
+    call print_char
+
+    mov bx, [DAPACK.count]
+    call print_hex
+
+    mov al, ' '
+    call print_char
+
+    mov bx, [DAPACK.seg]
+    call print_hex
+
+    mov al, ':'
+    call print_char
+
+    mov bx, [DAPACK.buf]
+    call print_hex
+
+    call print_line
+
+    ret
+
+error_chs:
+    mov ah, 0
+
+error:
+    call print_line
+
+    mov bh, 0
+    mov bl, ah
+    call print_hex
+
+    mov al, ' '
+    call print_char
+
+    mov si, error_msg
+    call print
+    call print_line
+.halt:
+    cli
+    hlt
+    jmp .halt
+
+%include "print.asm"
+
+stage_msg: db "Stage ",0
+error_msg: db "ERROR",0
+
+disk: db 0
+
+chs:
+.c: dd 0
+.h: dd 0
+.s: dd 0
+
+DAPACK:
+        db 0x10
+        db 0
+.count: dw 0 ; int 13 resets this to # of blocks actually read/written
+.buf:   dw 0 ; memory buffer destination address (0:7c00)
+.seg:   dw 0 ; in memory page zero
+.addr:  dq 0 ; put the lba to read in this spot
+
+times 446-($-$$) db 0
+partitions: times 4 * 16 db 0
+db 0x55
+db 0xaa

asm/x86-unknown-none/stage2.asm

@@ -0,0 +1,134 @@
+SECTION .text
+USE16
+
+stage2.entry:
+    ; check for required features
+    call cpuid_check
+
+    ; enable A20-Line via IO-Port 92, might not work on all motherboards
+    in al, 0x92
+    or al, 2
+    out 0x92, al
+
+    mov dword [protected_mode.func], stage3.entry
+    jmp protected_mode.entry
+
+%include "cpuid.asm"
+%include "gdt.asm"
+%include "long_mode.asm"
+%include "protected_mode.asm"
+%include "thunk.asm"
+
+USE32
+
+stage3.entry:
+    ; stage3 stack at 448 KiB (512KiB minus 64KiB disk buffer)
+    mov esp, 0x70000
+
+    ; push arguments
+    mov eax, thunk.int16
+    push eax
+    mov eax, thunk.int15
+    push eax
+    mov eax, thunk.int13
+    push eax
+    mov eax, thunk.int10
+    push eax
+    xor eax, eax
+    mov al, [disk]
+    push eax
+    mov eax, kernel.entry
+    push eax
+    mov eax, [stage3 + 0x18]
+    call eax
+.halt:
+    cli
+    hlt
+    jmp .halt
+
+kernel:
+.stack: dq 0
+.func: dq 0
+.args: dq 0
+
+.entry:
+    ; page_table: usize
+    mov eax, [esp + 4]
+    mov [long_mode.page_table], eax
+
+    ; stack: u64
+    mov eax, [esp + 8]
+    mov [.stack], eax
+    mov eax, [esp + 12]
+    mov [.stack + 4], eax
+
+    ; func: u64
+    mov eax, [esp + 16]
+    mov [.func], eax
+    mov eax, [esp + 20]
+    mov [.func + 4], eax
+
+    ; args: *const KernelArgs
+    mov eax, [esp + 24]
+    mov [.args], eax
+
+    ; long_mode: usize
+    mov eax, [esp + 28]
+    test eax, eax
+    jz .inner32
+
+    mov eax, .inner64
+    mov [long_mode.func], eax
+    jmp long_mode.entry
+
+.inner32:
+    ; disable paging
+    mov eax, cr0
+    and eax, 0x7FFFFFFF
+    mov cr0, eax
+
+    ;TODO: PAE (1 << 5)
+    ; enable FXSAVE/FXRSTOR, Page Global, and Page Size Extension
+    mov eax, cr4
+    or eax, 1 << 9 | 1 << 7 | 1 << 4
+    mov cr4, eax
+
+    ; set page table
+    mov eax, [long_mode.page_table]
+    mov cr3, eax
+
+    ; enabling paging and protection simultaneously
+    mov eax, cr0
+    ; Bit 31: Paging, Bit 16: write protect kernel, Bit 0: Protected Mode
+    or eax, 1 << 31 | 1 << 16 | 1
+    mov cr0, eax
+    
+    ; enable FPU
+    ;TODO: move to Rust
+    mov eax, cr0
+    and al, 11110011b ; Clear task switched (3) and emulation (2)
+    or al, 00100010b ; Set numeric error (5) monitor co-processor (1)
+    mov cr0, eax
+    fninit
+
+    mov esp, [.stack]
+    mov eax, [.args]
+    push eax
+    mov eax, [.func]
+    call eax
+.halt32:
+    cli
+    hlt
+    jmp .halt32
+
+USE64
+
+.inner64:
+    mov rsp, [.stack]
+    mov rax, [.func]
+    mov rdi, [.args]
+    call rax
+.halt64:
+    cli
+    hlt
+    jmp .halt64

asm/x86-unknown-none/thunk.asm

@@ -0,0 +1,149 @@
+SECTION .text
+USE32
+
+thunk:
+.int10:
+    mov dword [.func], .int10_real
+    jmp .enter
+
+.int13:
+    mov dword [.func], .int13_real
+    jmp .enter
+
+.int15:
+    mov dword [.func], .int15_real
+    jmp .enter
+
+.int16:
+    mov dword [.func], .int16_real
+    jmp .enter
+
+.func: dd 0
+.esp: dd 0
+.cr0: dd 0
+
+.enter:
+    ; save flags
+    pushfd
+
+    ; save registers
+    pushad
+
+    ; save esp
+    mov [.esp], esp
+
+    ; load gdt
+    lgdt [gdtr]
+
+    ; far jump to protected mode 16-bit
+    jmp gdt.pm16_code:.pm16
+
+.exit:
+    ; set segment selectors to 32-bit protected mode
+    mov eax, gdt.pm32_data
+    mov ds, eax
+    mov es, eax
+    mov fs, eax
+    mov gs, eax
+    mov ss, eax
+
+    ; restore esp
+    mov esp, [.esp]
+
+    ; restore registers
+    popad
+
+    ; restore flags
+    popfd
+
+    ; return
+    ret
+
+USE16
+
+.int10_real:
+    int 0x10
+    ret
+
+.int13_real:
+    int 0x13
+    ret
+
+.int15_real:
+    int 0x15
+    ret
+
+.int16_real:
+    int 0x16
+    ret
+
+.pm16:
+    ; set segment selectors to protected mode 16-bit
+    mov eax, gdt.pm16_data
+    mov ds, eax
+    mov es, eax
+    mov fs, eax
+    mov gs, eax
+    mov ss, eax
+
+    ; save cr0
+    mov eax, cr0
+    mov [.cr0], eax
+
+    ; disable paging and protected mode
+    and eax, 0x7FFFFFFE
+    mov cr0, eax
+
+    ; far jump to real mode
+    jmp 0:.real
+
+.real:
+    ; set segment selectors to real mode
+    mov eax, 0
+    mov ds, eax
+    mov es, eax
+    mov fs, eax
+    mov gs, eax
+    mov ss, eax
+
+    ; set stack
+    mov esp, 0x7C00 - 64
+
+    ; load registers and ES
+    pop es
+    pop edi
+    pop esi
+    pop ebp
+    pop ebx
+    pop edx
+    pop ecx
+    pop eax
+
+    ; enable interrupts
+    sti
+
+    ; call real mode function
+    call [.func]
+
+    ; disable interrupts
+    cli
+
+    ; save registers and ES
+    push eax
+    push ecx
+    push edx
+    push ebx
+    push ebp
+    push esi
+    push edi
+    push es
+
+    ; load gdt (BIOS sometimes overwrites this)
+    lgdt [gdtr]
+
+    ; restore cr0, will enable protected mode
+    mov eax, [.cr0]
+    mov cr0, eax
+
+    ; far jump to protected mode 32-bit
+    jmp gdt.pm32_code:.exit

linkers/riscv64-unknown-uefi.ld

@@ -0,0 +1,78 @@
+OUTPUT_FORMAT("elf64-littleriscv", "elf64-littleriscv", "elf64-littleriscv")
+OUTPUT_ARCH(riscv)
+ENTRY(coff_start)
+SECTIONS
+{
+  PROVIDE(ImageBase = .);
+  . = SEGMENT_START("text-segment", 0) + SIZEOF_HEADERS;
+  .note.gnu.build-id  : { *(.note.gnu.build-id) }
+  .hash           : { *(.hash) *(.gnu.hash) }
+
+  . = ALIGN(4096);
+  .text :
+  {
+    PROVIDE(_text = .);
+    *(.text.unlikely .text.*_unlikely .text.unlikely.*)
+    *(.text.exit .text.exit.*)
+    *(.text.startup .text.startup.*)
+    *(.text.hot .text.hot.*)
+    *(SORT(.text.sorted.*))
+    *(.text .stub .text.* .gnu.linkonce.t.*)
+    /* .gnu.warning sections are handled specially by elf.em.  */
+    *(.gnu.warning)
+  }
+  PROVIDE (__etext = .);
+  PROVIDE (_etext = .);
+  PROVIDE (etext = .);
+  . = ALIGN(4096);
+
+  .rdata :
+   {
+     *(.rodata .rodata.* .gnu.linkonce.r.*)
+     *(.rodata1)
+     KEEP (*(.eh_frame))
+     *(.eh_frame.*)
+     *(.dynamic)
+   }
+  . = ALIGN(4096);
+  .data :
+  {
+    *(.got) *(.igot)
+    *(.got.plt) *(.igot.plt)
+    *(.data .data.* .gnu.linkonce.d.*)
+    *(.data1)
+    *(.srodata.cst16) *(.srodata.cst8) *(.srodata.cst4) *(.srodata.cst2) *(.srodata .srodata.*)
+    *(.sdata2 .sdata2.* .gnu.linkonce.s2.*)
+    *(.sdata .sdata.* .gnu.linkonce.s.*)
+  PROVIDE (_edata = .); PROVIDE (edata = .);
+  . = ALIGN(4096);
+  PROVIDE (__bss_start = .);
+    *(.sbss2 .sbss2.* .gnu.linkonce.sb2.*)
+    *(.dynsbss)
+    *(.sbss .sbss.* .gnu.linkonce.sb.*)
+    *(.scommon)
+   *(.dynbss)
+   *(.bss .bss.* .gnu.linkonce.b.*)
+   *(COMMON)
+  . = ALIGN(4096);
+  }
+  .reloc :
+  {
+    KEEP(*(.reloc*))
+  }
+  .rela :
+   {
+     *(.rela.*)
+   }
+  .data.rel.ro :
+   {
+     *(.data.rel.ro.local* .gnu.linkonce.d.rel.ro.local.*)
+     *(.data.rel.ro .data.rel.ro.* .gnu.linkonce.d.rel.ro.*)
+   }
+  . = ALIGN(4096);
+
+  .dynsym         : { *(.dynsym) }
+  .dynstr         : { *(.dynstr) }
+
+   /DISCARD/ : { *(.note.GNU-stack) *(.gnu_debuglink) *(.gnu.lto_*) }
+}

linkers/x86-unknown-none.ld

@@ -0,0 +1,57 @@
+ENTRY(start)
+OUTPUT_FORMAT(elf32-i386)
+
+SECTIONS {
+    /* The start address must match bootloader.asm */
+    . = 0x13000;
+
+    . += SIZEOF_HEADERS;
+    . = ALIGN(4096);
+
+    .text : {
+        __text_start = .;
+        *(.text*)
+        . = ALIGN(4096);
+        __text_end = .;
+    }
+
+    .rodata : {
+        __rodata_start = .;
+        *(.rodata*)
+        . = ALIGN(4096);
+        __rodata_end = .;
+    }
+
+    .data : {
+        __data_start = .;
+        *(.data*)
+        . = ALIGN(4096);
+        __data_end = .;
+        __bss_start = .;
+        *(.bss*)
+        . = ALIGN(4096);
+        __bss_end = .;
+    }
+
+    .tdata : {
+        __tdata_start = .;
+        *(.tdata*)
+        . = ALIGN(4096);
+        __tdata_end = .;
+        __tbss_start = .;
+        *(.tbss*)
+        . += 8;
+        . = ALIGN(4096);
+        __tbss_end = .;
+    }
+
+    __end = .;
+
+    /DISCARD/ : {
+        *(.comment*)
+        *(.eh_frame*)
+        *(.gcc_except_table*)
+        *(.note*)
+        *(.rel.eh_frame*)
+    }
+}

mk/aarch64-unknown-uefi.mk

@@ -0,0 +1,69 @@
+export PARTED?=parted
+export QEMU?=qemu-system-aarch64
+
+all: $(BUILD)/bootloader.efi
+
+$(BUILD)/bootloader.efi: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target $(TARGET) \
+		--bin bootloader \
+		--release \
+		-- \
+		--emit link="$@"
+
+$(BUILD)/bootloader-live.efi: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target $(TARGET) \
+		--bin bootloader \
+		--release \
+		--features live \
+		-- \
+		--emit link="$@"
+
+$(BUILD)/esp.bin: $(BUILD)/bootloader.efi
+	rm -f "$@.partial"
+	fallocate -l 64MiB "$@.partial"
+	mkfs.vfat -F 32 "$@.partial"
+	mmd -i "$@.partial" efi
+	mmd -i "$@.partial" efi/boot
+	mcopy -i "$@.partial" "$<" ::efi/boot/bootaa64.efi
+	mv "$@.partial" "$@"
+
+$(BUILD)/harddrive.bin: $(BUILD)/esp.bin $(BUILD)/filesystem.bin
+	rm -f "$@.partial"
+	fallocate -l 320MiB "$@.partial"
+	$(PARTED) -s -a minimal "$@.partial" mklabel gpt
+	$(PARTED) -s -a minimal "$@.partial" mkpart ESP FAT32 1MiB 65MiB
+	$(PARTED) -s -a minimal "$@.partial" mkpart REDOXFS 65MiB 100%
+	$(PARTED) -s -a minimal "$@.partial" toggle 1 boot
+	dd if="$(BUILD)/esp.bin" of="$@.partial" bs=1MiB seek=1 conv=notrunc
+	dd if="$(BUILD)/filesystem.bin" of="$@.partial" bs=1MiB seek=65 conv=notrunc
+	mv "$@.partial" "$@"
+
+$(BUILD)/firmware.rom: /usr/share/AAVMF/AAVMF_CODE.fd
+	cp "$<" "$@"
+
+qemu: $(BUILD)/harddrive.bin $(BUILD)/firmware.rom
+	$(QEMU) \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-device virtio-gpu-pci \
+		-machine virt \
+		-net none \
+		-cpu max \
+		-bios "$(BUILD)/firmware.rom" \
+		-drive file="$<",format=raw

mk/riscv64gc-unknown-uefi.mk

@@ -0,0 +1,108 @@
+LD=riscv64-unknown-redox-ld
+OBJCOPY=riscv64-unknown-redox-objcopy
+SCRIPT=$(SOURCE)/linkers/riscv64-unknown-uefi.ld
+PARTED?=parted
+QEMU?=qemu-system-riscv64
+
+all: $(BUILD)/bootloader.efi
+
+$(BUILD)/%.efi: $(BUILD)/%.efi.elf $(BUILD)/%.efi.sym
+	$(OBJCOPY) -j .text -j .data -j .rdata -j .rela -j .reloc --target pei-riscv64-little \
+	           --file-alignment 512 --section-alignment 4096 --subsystem 10 "$<" "$@"
+
+.PRECIOUS: $(BUILD)/%.efi.sym
+$(BUILD)/%.efi.sym: $(BUILD)/%.efi.elf
+	$(OBJCOPY) --only-keep-debug "$<" "$@"
+
+$(BUILD)/%.efi.elf: $(BUILD)/%.a $(SCRIPT)
+	$(LD) --gc-sections -z max-page-size=0x1000 --warn-common --no-undefined -z nocombreloc -shared \
+	      --fatal-warnings -Bsymbolic --entry coff_start -T "$(SCRIPT)" -o "$@" "$<"
+
+$(BUILD)/bootloader.a: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target $(TARGET) \
+		--lib \
+		--release \
+		-- \
+		--emit link=$@
+
+$(BUILD)/bootloader-live.a: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target $(TARGET) \
+		--lib \
+		--release \
+		--features live \
+		-- \
+		--emit link=$@
+
+
+$(BUILD)/esp.bin: $(BUILD)/bootloader.efi
+	rm -f $@.partial
+	fallocate -l 64MiB $@.partial
+	mkfs.vfat -F 32 $@.partial
+	mmd -i $@.partial EFI
+	mmd -i $@.partial EFI/BOOT
+	mcopy -i $@.partial $< ::EFI/BOOT/BOOTRISCV64.EFI
+	mv $@.partial $@
+
+$(BUILD)/harddrive.bin: $(BUILD)/esp.bin $(BUILD)/filesystem.bin
+	rm -f $@.partial
+	fallocate -l 320MiB $@.partial
+	$(PARTED) -s -a minimal $@.partial mklabel gpt
+	$(PARTED) -s -a minimal $@.partial mkpart ESP FAT32 1MiB 65MiB
+	$(PARTED) -s -a minimal $@.partial mkpart REDOXFS 65MiB 100%
+	$(PARTED) -s -a minimal $@.partial toggle 1 boot
+	dd if=$(BUILD)/esp.bin of=$@.partial bs=1MiB seek=1 conv=notrunc
+	dd if=$(BUILD)/filesystem.bin of=$@.partial bs=1MiB seek=65 conv=notrunc
+	mv $@.partial $@
+
+$(BUILD)/fw_vars.img: /usr/share/qemu-efi-riscv64/RISCV_VIRT_VARS.fd
+	cp "$<" "$@"
+
+$(BUILD)/firmware.rom: /usr/share/qemu-efi-riscv64/RISCV_VIRT_CODE.fd
+	cp "$<" "$@"
+
+qemu-acpi: $(BUILD)/harddrive.bin $(BUILD)/firmware.rom $(BUILD)/fw_vars.img
+	$(QEMU) \
+	    -M virt \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-device virtio-gpu-pci \
+		-machine virt \
+		-net none \
+		-cpu max \
+		-drive if=pflash,format=raw,unit=0,file=$(BUILD)/firmware.rom,readonly=on \
+		-drive if=pflash,format=raw,unit=1,file=$(BUILD)/fw_vars.img \
+		-drive file=$(BUILD)/harddrive.bin,format=raw,if=virtio
+
+
+qemu-dtb: $(BUILD)/harddrive.bin $(BUILD)/firmware.rom $(BUILD)/fw_vars.img
+	$(QEMU) \
+	    -M virt,acpi=off \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-device virtio-gpu-pci \
+		-machine virt \
+		-net none \
+		-cpu max \
+		-drive if=pflash,format=raw,unit=0,file=$(BUILD)/firmware.rom,readonly=on \
+		-drive if=pflash,format=raw,unit=1,file=$(BUILD)/fw_vars.img \
+		-drive file=$(BUILD)/harddrive.bin,format=raw,if=virtio -s

mk/x86-unknown-none.mk

@@ -0,0 +1,65 @@
+export LD?=ld
+export OBJCOPY?=objcopy
+export PARTED?=parted
+export QEMU?=qemu-system-x86_64
+
+all: $(BUILD)/bootloader.bin
+
+$(BUILD)/libbootloader.a: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft -Zunstable-options" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target "$(TARGET)" \
+		--lib \
+		--release \
+		-- \
+		--emit link="$@"
+
+$(BUILD)/libbootloader-live.a: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft -Zunstable-options" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target "$(TARGET)" \
+		--lib \
+		--release \
+		--features live \
+		-- \
+		--emit link="$@"
+
+$(BUILD)/%.elf: $(BUILD)/lib%.a $(SOURCE)/linkers/$(TARGET).ld
+	$(LD) -m elf_i386 --gc-sections -z max-page-size=0x1000 -T "$(SOURCE)/linkers/$(TARGET).ld" -o "$@" "$<"
+	$(OBJCOPY) --only-keep-debug "$@" "$@.sym"
+	$(OBJCOPY) --strip-debug "$@"
+
+$(BUILD)/%.bin: $(BUILD)/%.elf $(shell find $(SOURCE)/asm/$(TARGET) -type f)
+	nasm -f bin -o "$@" -l "$@.lst" -D STAGE3="$<" -i"$(SOURCE)/asm/$(TARGET)/" "$(SOURCE)/asm/$(TARGET)/bootloader.asm"
+
+$(BUILD)/harddrive.bin: $(BUILD)/bootloader.bin $(BUILD)/filesystem.bin
+	rm -f "$@.partial"
+	fallocate -l 256MiB "$@.partial"
+	$(PARTED) -s -a minimal "$@.partial" mklabel msdos
+	$(PARTED) -s -a minimal "$@.partial" mkpart primary 2MiB 100%
+	dd if="$<" of="$@.partial" bs=1 count=446 conv=notrunc
+	dd if="$<" of="$@.partial" bs=512 skip=1 seek=1 conv=notrunc
+	dd if="$(BUILD)/filesystem.bin" of="$@.partial" bs=1MiB seek=2 conv=notrunc
+	mv "$@.partial" "$@"
+
+qemu: $(BUILD)/harddrive.bin
+	$(QEMU) \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-machine q35 \
+		-net none \
+		-enable-kvm \
+		-cpu host \
+		-drive file="$<",format=raw

mk/x86_64-unknown-uefi.mk

@@ -0,0 +1,70 @@
+export PARTED?=parted
+export QEMU?=qemu-system-x86_64
+
+all: $(BUILD)/bootloader.efi
+
+$(BUILD)/bootloader.efi: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p "$(BUILD)"
+	env RUSTFLAGS="--cfg aes_force_soft" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target $(TARGET) \
+		--bin bootloader \
+		--release \
+		-- \
+		--emit link="$@"
+
+$(BUILD)/bootloader-live.efi: $(SOURCE)/Cargo.toml $(SOURCE)/Cargo.lock $(shell find $(SOURCE)/src -type f)
+	mkdir -p $(BUILD)
+	cd "$(SOURCE)"
+	env RUSTFLAGS="--cfg aes_force_soft" \
+	cargo rustc \
+		--manifest-path="$<" \
+		-Z build-std=core,alloc \
+		-Z build-std-features=compiler-builtins-mem \
+		--target $(TARGET) \
+		--bin bootloader \
+		--release \
+		--features live \
+		-- \
+		--emit link="$@"
+
+$(BUILD)/esp.bin: $(BUILD)/bootloader.efi
+	rm -f "$@.partial"
+	fallocate -l 1MiB $@.partial
+	mkfs.vfat "$@.partial"
+	mmd -i "$@.partial" efi
+	mmd -i "$@.partial" efi/boot
+	mcopy -i "$@.partial" "$<" ::efi/boot/bootx64.efi
+	mv "$@.partial" "$@"
+
+$(BUILD)/harddrive.bin: $(BUILD)/esp.bin $(BUILD)/filesystem.bin
+	rm -f "$@.partial"
+	fallocate -l 320MiB "$@.partial"
+	$(PARTED) -s -a minimal "$@.partial" mklabel gpt
+	$(PARTED) -s -a minimal "$@.partial" mkpart ESP FAT32 1MiB 2MiB
+	$(PARTED) -s -a minimal "$@.partial" mkpart REDOXFS 2MiB 100%
+	$(PARTED) -s -a minimal "$@.partial" toggle 1 boot
+	dd if="$(BUILD)/esp.bin" of="$@.partial" bs=1MiB seek=1 conv=notrunc
+	dd if="$(BUILD)/filesystem.bin" of="$@.partial" bs=1MiB seek=2 conv=notrunc
+	mv "$@.partial" "$@"
+
+$(BUILD)/firmware.rom: /usr/share/OVMF/OVMF_CODE.fd
+	cp "$<" "$@"
+
+qemu: $(BUILD)/harddrive.bin $(BUILD)/firmware.rom
+	$(QEMU) \
+		-d cpu_reset \
+		-no-reboot \
+		-smp 4 -m 2048 \
+		-chardev stdio,id=debug,signal=off,mux=on \
+		-serial chardev:debug \
+		-mon chardev=debug \
+		-machine q35 \
+		-net none \
+		-enable-kvm \
+		-cpu host \
+		-bios "$(BUILD)/firmware.rom" \
+		-drive file="$<",format=raw

rust-toolchain.toml

@@ -0,0 +1,3 @@
+[toolchain]
+channel = "nightly-2025-10-03"
+components = ["rust-src"]

src/arch/aarch64.rs

@@ -0,0 +1,154 @@
+use crate::area_add;
+use crate::os::{Os, OsMemoryEntry, OsMemoryKind, dtb::is_in_dev_mem_region};
+use core::slice;
+
+pub(crate) const PF_PRESENT: u64 = 1 << 0;
+pub(crate) const PF_TABLE: u64 = 1 << 1;
+pub(crate) const PF_OUTER_SHAREABLE: u64 = 0b01 << 8;
+pub(crate) const PF_INNER_SHAREABLE: u64 = 0b11 << 8;
+pub(crate) const PF_ACCESS: u64 = 1 << 10;
+
+pub(crate) const PF_DEV: u64 = PF_OUTER_SHAREABLE | 2 << 2;
+pub(crate) const PF_RAM: u64 = PF_INNER_SHAREABLE;
+
+pub(crate) const ENTRY_ADDRESS_MASK: u64 = 0x000F_FFFF_FFFF_F000;
+pub(crate) const PAGE_ENTRIES: usize = 512;
+const PAGE_SIZE: usize = 4096;
+pub(crate) const PHYS_OFFSET: u64 = 0xFFFF_8000_0000_0000;
+
+unsafe fn paging_allocate(os: &impl Os) -> Option<&'static mut [u64]> {
+    unsafe {
+        let ptr = os.alloc_zeroed_page_aligned(PAGE_SIZE);
+        if !ptr.is_null() {
+            area_add(OsMemoryEntry {
+                base: ptr as u64,
+                size: PAGE_SIZE as u64,
+                kind: OsMemoryKind::Reclaim,
+            });
+            Some(slice::from_raw_parts_mut(ptr as *mut u64, PAGE_ENTRIES))
+        } else {
+            None
+        }
+    }
+}
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        // Create L0
+        let l0 = paging_allocate(os)?;
+
+        {
+            // Create L1 for identity mapping
+            let l1 = paging_allocate(os)?;
+
+            // Link first user and first kernel L0 entry to L1
+            l0[0] = l1.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+            l0[256] = l1.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+
+            // Identity map 8 GiB using 1 GiB pages
+            for l1_i in 0..8 {
+                let addr = l1_i as u64 * 0x4000_0000;
+                //TODO: is PF_RAM okay?
+                l1[l1_i] = addr | PF_ACCESS | PF_DEV | PF_PRESENT;
+            }
+        }
+
+        {
+            // Create L1 for kernel mapping
+            let l1 = paging_allocate(os)?;
+
+            // Link second to last L0 entry to L1
+            l0[510] = l1.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+
+            // Map kernel_size at kernel offset
+            let mut kernel_mapped = 0;
+            let mut l1_i = 0;
+            while kernel_mapped < kernel_size && l1_i < l1.len() {
+                let l2 = paging_allocate(os)?;
+                l1[l1_i] = l2.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+                l1_i += 1;
+
+                let mut l2_i = 0;
+                while kernel_mapped < kernel_size && l2_i < l2.len() {
+                    let l3 = paging_allocate(os)?;
+                    l2[l2_i] = l3.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+                    l2_i += 1;
+
+                    let mut l3_i = 0;
+                    while kernel_mapped < kernel_size && l3_i < l3.len() {
+                        let addr = kernel_phys + kernel_mapped;
+                        l3[l3_i] = addr | PF_ACCESS | PF_RAM | PF_TABLE | PF_PRESENT;
+                        l3_i += 1;
+                        kernel_mapped += PAGE_SIZE as u64;
+                    }
+                }
+            }
+            assert!(kernel_mapped >= kernel_size);
+        }
+
+        Some(l0.as_ptr() as usize)
+    }
+}
+
+pub unsafe fn paging_framebuffer(
+    os: &impl Os,
+    page_phys: usize,
+    framebuffer_phys: u64,
+    framebuffer_size: u64,
+) -> Option<u64> {
+    unsafe {
+        //TODO: smarter test for framebuffer already mapped
+        if framebuffer_phys + framebuffer_size <= 0x2_0000_0000 {
+            return Some(framebuffer_phys + PHYS_OFFSET);
+        }
+
+        let l0_i = ((framebuffer_phys / 0x80_0000_0000) + 256) as usize;
+        let mut l1_i = ((framebuffer_phys % 0x80_0000_0000) / 0x4000_0000) as usize;
+        let mut l2_i = ((framebuffer_phys % 0x4000_0000) / 0x20_0000) as usize;
+        let mut l3_i = ((framebuffer_phys % 0x20_0000) / (PAGE_SIZE as u64)) as usize;
+        assert_eq!(framebuffer_phys % (PAGE_SIZE as u64), 0);
+
+        let l0 = slice::from_raw_parts_mut(page_phys as *mut u64, PAGE_ENTRIES);
+
+        // Create l1 for framebuffer mapping
+        let l1 = if l0[l0_i] == 0 {
+            let l1 = paging_allocate(os)?;
+            l0[l0_i] = l1.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+            l1
+        } else {
+            slice::from_raw_parts_mut((l0[l0_i] & ENTRY_ADDRESS_MASK) as *mut u64, PAGE_ENTRIES)
+        };
+
+        // Map framebuffer_size at framebuffer offset
+        let mut framebuffer_mapped = 0;
+        while framebuffer_mapped < framebuffer_size && l1_i < l1.len() {
+            let l2 = paging_allocate(os)?;
+            assert_eq!(l1[l1_i], 0);
+            l1[l1_i] = l2.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+
+            while framebuffer_mapped < framebuffer_size && l2_i < l2.len() {
+                let l3 = paging_allocate(os)?;
+                assert_eq!(l2[l2_i], 0);
+                l2[l2_i] = l3.as_ptr() as u64 | PF_ACCESS | PF_TABLE | PF_PRESENT;
+
+                while framebuffer_mapped < framebuffer_size && l3_i < l3.len() {
+                    let addr = framebuffer_phys + framebuffer_mapped;
+                    assert_eq!(l3[l3_i], 0);
+                    //TODO: is PF_RAM okay?
+                    l3[l3_i] = addr | PF_ACCESS | PF_RAM | PF_TABLE | PF_PRESENT;
+                    framebuffer_mapped += PAGE_SIZE as u64;
+                    l3_i += 1;
+                }
+
+                l2_i += 1;
+                l3_i = 0;
+            }
+
+            l1_i += 1;
+            l2_i = 0;
+        }
+        assert!(framebuffer_mapped >= framebuffer_size);
+
+        Some(framebuffer_phys + PHYS_OFFSET)
+    }
+}

src/arch/mod.rs

@@ -0,0 +1,17 @@
+#[cfg(target_arch = "aarch64")]
+pub use self::aarch64::*;
+
+#[cfg(target_arch = "aarch64")]
+mod aarch64;
+
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+pub use self::x86::*;
+
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+mod x86;
+
+#[cfg(target_arch = "riscv64")]
+pub use self::riscv64::*;
+
+#[cfg(target_arch = "riscv64")]
+mod riscv64;

src/arch/riscv64/mod.rs

@@ -0,0 +1,59 @@
+use core::slice;
+
+use crate::area_add;
+use crate::os::{Os, OsMemoryEntry, OsMemoryKind};
+
+pub(crate) mod sv39;
+pub(crate) mod sv48;
+pub(crate) mod sv57;
+
+// Common constants
+const PAGE_SHIFT: usize = 12;
+const TABLE_SHIFT: usize = 9;
+const TABLE_MASK: usize = (1 << TABLE_SHIFT) - 1;
+const PAGE_ENTRIES: usize = 512;
+const PAGE_SIZE: usize = 4096;
+const PHYS_MASK: usize = (1usize << 44) - 1;
+
+const VALID: u64 = 1;
+const RWX: u64 = 7 << 1;
+const ACCESSED: u64 = 1 << 6;
+const DIRTY: u64 = 1 << 7;
+
+extern crate alloc;
+
+pub(crate) use sv39::PHYS_OFFSET;
+pub(crate) use sv39::SATP_BITS;
+pub(crate) use sv39::paging_create;
+pub(crate) use sv39::paging_physmem as paging_framebuffer;
+
+unsafe fn paging_allocate(os: &impl Os) -> Option<&'static mut [u64]> {
+    unsafe {
+        let ptr = os.alloc_zeroed_page_aligned(PAGE_SIZE);
+        if !ptr.is_null() {
+            area_add(OsMemoryEntry {
+                base: ptr as u64,
+                size: PAGE_SIZE as u64,
+                kind: OsMemoryKind::Reclaim,
+            });
+            Some(slice::from_raw_parts_mut(ptr as *mut u64, PAGE_ENTRIES))
+        } else {
+            None
+        }
+    }
+}
+
+unsafe fn get_table(os: &impl Os, parent: &mut [u64], index: usize) -> Option<&'static mut [u64]> {
+    unsafe {
+        if parent[index] == 0 {
+            let table = paging_allocate(os)?;
+            parent[index] = table.as_ptr() as u64 >> 2 | VALID;
+            Some(table)
+        } else {
+            Some(slice::from_raw_parts_mut(
+                (((parent[index] >> 10) & PHYS_MASK as u64) << 12) as *mut u64,
+                PAGE_ENTRIES,
+            ))
+        }
+    }
+}

src/arch/riscv64/sv39.rs

@@ -0,0 +1,90 @@
+use core::slice;
+
+use super::*;
+use crate::os::Os;
+
+// Sv39 scheme
+
+pub(crate) const PHYS_OFFSET: u64 = 0xFFFF_FFC0_0000_0000;
+pub(crate) const SATP_BITS: usize = 8;
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        // Create L2
+        let l2 = paging_allocate(os)?;
+
+        {
+            // Create L1 for identity mapping
+            for l2_i in 0..8 {
+                let addr = l2_i as u64 * 0x4000_0000;
+                // Identity map 8 GiB using 1GB pages
+                l2[l2_i] = addr >> 2 | RWX | VALID | ACCESSED | DIRTY;
+                // map phys into kernel VAS
+                l2[(PAGE_ENTRIES / 2) + l2_i] = addr >> 2 | RWX | VALID | ACCESSED | DIRTY;
+            }
+        }
+
+        {
+            // Create L1 for kernel mapping
+            let l1 = paging_allocate(os)?;
+
+            // Link second to last L0 entry to L1
+            l2[510] = l1.as_ptr() as u64 >> 2 | VALID;
+
+            // Map kernel_size at kernel offset
+            let mut kernel_mapped = 0;
+            let mut l1_i = 0;
+            while kernel_mapped < kernel_size && l1_i < l1.len() {
+                let l0 = paging_allocate(os)?;
+                l1[l1_i] = l0.as_ptr() as u64 >> 2 | VALID;
+                l1_i += 1;
+
+                let mut l0_i = 0;
+                while kernel_mapped < kernel_size && l0_i < l2.len() {
+                    let addr = kernel_phys + kernel_mapped;
+                    l0[l0_i] = addr >> 2 | RWX | VALID | ACCESSED | DIRTY;
+                    l0_i += 1;
+                    kernel_mapped += PAGE_SIZE as u64;
+                }
+            }
+            assert!(kernel_mapped >= kernel_size);
+        }
+
+        Some(l2.as_ptr() as usize)
+    }
+}
+
+pub unsafe fn paging_physmem(os: &impl Os, page_phys: usize, phys: u64, size: u64) -> Option<u64> {
+    unsafe {
+        if phys + size <= 0x2_0000_0000 {
+            return Some(phys + PHYS_OFFSET);
+        }
+
+        let mut l1_i = (phys as usize >> (PAGE_SHIFT + 2 * TABLE_SHIFT)) + PAGE_ENTRIES / 2;
+        let mut l0_i = (phys as usize >> (PAGE_SHIFT + TABLE_SHIFT)) & TABLE_MASK;
+        assert_eq!(phys & ((1 << (PAGE_SHIFT + TABLE_SHIFT)) - 1), 0);
+
+        let l1 = slice::from_raw_parts_mut(page_phys as *mut u64, PAGE_ENTRIES);
+
+        // Map framebuffer_size at framebuffer offset
+        let mut mapped = 0;
+        while mapped < size && l1_i < l1.len() {
+            let l0 = get_table(os, l1, l1_i)?;
+
+            while mapped < size && l0_i < l0.len() {
+                let addr = phys + mapped;
+                assert_eq!(l0[l0_i], 0);
+                l0[l0_i] = (addr >> 2) | RWX | VALID | ACCESSED | DIRTY;
+                mapped += 1 << (PAGE_SHIFT + TABLE_SHIFT); // Map with 2mb mega-pages
+                l0_i += 1;
+            }
+
+            l1_i += 1;
+            l0_i = 0;
+        }
+
+        assert!(mapped >= size);
+
+        Some(phys + PHYS_OFFSET)
+    }
+}

src/arch/riscv64/sv48.rs

@@ -0,0 +1,108 @@
+use core::slice;
+
+use super::*;
+use crate::os::Os;
+
+// Sv48 scheme
+
+pub(crate) const PHYS_OFFSET: u64 = 0xFFFF_8000_0000_0000;
+pub(crate) const SATP_BITS: usize = 9;
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        // Create L3
+        let l3 = paging_allocate(os)?;
+
+        {
+            // Create L2 for identity mapping
+            let l2 = paging_allocate(os)?;
+
+            // Map L2 into beginning of userspace and kernelspace
+            l3[0] = (l2.as_ptr() as u64 >> 2) | VALID;
+            l3[PAGE_ENTRIES / 2] = (l2.as_ptr() as u64 >> 2) | VALID;
+
+            // Identity map 8 GiB using 1GB pages
+            for l2_i in 0..8 {
+                let addr = l2_i as u64 * 0x4000_0000;
+                l2[l2_i] = addr >> 2 | RWX | VALID;
+            }
+        }
+
+        {
+            // Create L2 for kernel mapping
+            let l2 = paging_allocate(os)?;
+
+            // Link last L3 entry to L2
+            l3[511] = l2.as_ptr() as u64 >> 2 | VALID;
+
+            // Create L1 for kernel mapping
+            let l1 = paging_allocate(os)?;
+
+            // Link last L1 entry to L2
+            l2[510] = l1.as_ptr() as u64 >> 2 | VALID;
+
+            // Map kernel_size at kernel offset
+            let mut kernel_mapped = 0;
+            let mut l1_i = 0;
+            while kernel_mapped < kernel_size && l1_i < l1.len() {
+                let l0 = paging_allocate(os)?;
+                l1[l1_i] = l0.as_ptr() as u64 >> 2 | VALID;
+                l1_i += 1;
+
+                let mut l0_i = 0;
+                while kernel_mapped < kernel_size && l0_i < l2.len() {
+                    let addr = kernel_phys + kernel_mapped;
+                    l0[l0_i] = addr >> 2 | RWX | VALID | ACCESSED | DIRTY;
+                    l0_i += 1;
+                    kernel_mapped += PAGE_SIZE as u64;
+                }
+            }
+            assert!(kernel_mapped >= kernel_size);
+        }
+
+        Some(l3.as_ptr() as usize)
+    }
+}
+
+pub unsafe fn paging_physmem(os: &impl Os, page_phys: usize, phys: u64, size: u64) -> Option<u64> {
+    unsafe {
+        if phys + size <= 0x2_0000_0000 {
+            return Some(phys + PHYS_OFFSET);
+        }
+
+        let mut l2_i = (phys as usize >> (PAGE_SHIFT + 3 * TABLE_SHIFT)) + PAGE_ENTRIES / 2;
+        let mut l1_i = (phys as usize >> (PAGE_SHIFT + 2 * TABLE_SHIFT)) & TABLE_MASK;
+        let mut l0_i = (phys as usize >> (PAGE_SHIFT + TABLE_SHIFT)) & TABLE_MASK;
+        assert_eq!(phys & ((1 << (PAGE_SHIFT + TABLE_SHIFT)) - 1), 0);
+
+        let l2 = slice::from_raw_parts_mut(page_phys as *mut u64, PAGE_ENTRIES);
+
+        // Map framebuffer_size at framebuffer offset
+        let mut mapped = 0;
+        while mapped < size && l2_i < l2.len() {
+            let l1 = get_table(os, l2, l2_i)?;
+
+            while mapped < size && l1_i < l1.len() {
+                let l0 = get_table(os, l1, l1_i)?;
+
+                while mapped < size && l0_i < l0.len() {
+                    let addr = phys + mapped;
+                    assert_eq!(l0[l0_i], 0);
+                    l0[l0_i] = (addr >> 2) | RWX | VALID;
+                    mapped += 1 << (PAGE_SHIFT + TABLE_SHIFT);
+                    l0_i += 1;
+                }
+
+                l1_i += 1;
+                l0_i = 0;
+            }
+
+            l2_i += 1;
+            l1_i = 0;
+        }
+
+        assert!(mapped >= size);
+
+        Some(phys + PHYS_OFFSET)
+    }
+}

src/arch/riscv64/sv57.rs

@@ -0,0 +1,124 @@
+use core::slice;
+
+use super::*;
+use crate::os::Os;
+
+// Sv57 scheme
+
+pub(crate) const PHYS_OFFSET: u64 = 0xFF00_0000_0000_0000;
+pub(crate) const SATP_BIT: usize = 10;
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        // Create L4
+        let l4 = paging_allocate(os)?;
+
+        {
+            // Create L3
+            let l3 = paging_allocate(os)?;
+
+            // Map L3 into beginning of userspace and kernelspace
+            l4[0] = (l3.as_ptr() as u64 >> 2) | VALID;
+            l4[PAGE_ENTRIES / 2] = (l3.as_ptr() as u64 >> 2) | VALID;
+
+            // Create L2 for identity mapping
+            let l2 = paging_allocate(os)?;
+
+            // Identity map 8 GiB using 1GB pages
+            for l2_i in 0..8 {
+                let addr = l2_i as u64 * 0x4000_0000;
+                l2[l2_i] = addr >> 2 | RWX | VALID;
+            }
+        }
+
+        {
+            // Create L3
+            let l3 = paging_allocate(os)?;
+
+            // Link last L4 entry to L3
+            l4[511] = l3.as_ptr() as u64 >> 2 | VALID;
+
+            // Create L2 for kernel mapping
+            let l2 = paging_allocate(os)?;
+
+            // Link last L3 entry to L2
+            l3[511] = l2.as_ptr() as u64 >> 2 | VALID;
+
+            // Create L1 for kernel mapping
+            let l1 = paging_allocate(os)?;
+
+            // Link last L1 entry to L2
+            l2[510] = l1.as_ptr() as u64 >> 2 | VALID;
+
+            // Map kernel_size at kernel offset
+            let mut kernel_mapped = 0;
+            let mut l1_i = 0;
+            while kernel_mapped < kernel_size && l1_i < l1.len() {
+                let l0 = paging_allocate(os)?;
+                l1[l1_i] = l0.as_ptr() as u64 >> 2 | VALID;
+                l1_i += 1;
+
+                let mut l0_i = 0;
+                while kernel_mapped < kernel_size && l0_i < l2.len() {
+                    let addr = kernel_phys + kernel_mapped;
+                    l0[l0_i] = addr >> 2 | RWX | VALID | ACCESSED | DIRTY;
+                    l0_i += 1;
+                    kernel_mapped += PAGE_SIZE as u64;
+                }
+            }
+            assert!(kernel_mapped >= kernel_size);
+        }
+
+        Some(l4.as_ptr() as usize)
+    }
+}
+
+pub unsafe fn paging_physmem(os: &impl Os, page_phys: usize, phys: u64, size: u64) -> Option<u64> {
+    unsafe {
+        if phys + size <= 0x2_0000_0000 {
+            return Some(phys + PHYS_OFFSET);
+        }
+        let mut l3_i = (phys as usize >> (PAGE_SHIFT + 4 * TABLE_SHIFT)) + PAGE_ENTRIES / 2;
+        let mut l2_i = (phys as usize >> (PAGE_SHIFT + 3 * TABLE_SHIFT)) & TABLE_MASK;
+        let mut l1_i = (phys as usize >> (PAGE_SHIFT + 2 * TABLE_SHIFT)) & TABLE_MASK;
+        let mut l0_i = (phys as usize >> (PAGE_SHIFT + TABLE_SHIFT)) & TABLE_MASK;
+        assert_eq!(phys & ((1 << (PAGE_SHIFT + TABLE_SHIFT)) - 1), 0);
+
+        let l3 = slice::from_raw_parts_mut(page_phys as *mut u64, PAGE_ENTRIES);
+
+        // Map framebuffer_size at framebuffer offset
+        let mut mapped = 0;
+
+        while mapped < size && l3_i < l3.len() {
+            let l2 = get_table(os, l3, l3_i)?;
+
+            while mapped < size && l2_i < l2.len() {
+                let l1 = get_table(os, l2, l2_i)?;
+
+                while mapped < size && l1_i < l1.len() {
+                    let l0 = get_table(os, l1, l1_i)?;
+
+                    while mapped < size && l0_i < l0.len() {
+                        let addr = phys + mapped;
+                        assert_eq!(l0[l0_i], 0);
+                        l0[l0_i] = (addr >> 2) | RWX | VALID;
+                        mapped += 1 << (PAGE_SHIFT + TABLE_SHIFT);
+                        l0_i += 1;
+                    }
+
+                    l1_i += 1;
+                    l0_i = 0;
+                }
+
+                l2_i += 1;
+                l1_i = 0;
+            }
+            l3_i += 1;
+            l2_i += 0;
+        }
+
+        assert!(mapped >= size);
+
+        Some(phys + PHYS_OFFSET)
+    }
+}

src/arch/x86/mod.rs

@@ -0,0 +1,29 @@
+use crate::os::Os;
+
+pub(crate) mod x32;
+pub(crate) mod x64;
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        if crate::KERNEL_64BIT {
+            x64::paging_create(os, kernel_phys, kernel_size)
+        } else {
+            x32::paging_create(os, kernel_phys, kernel_size)
+        }
+    }
+}
+
+pub unsafe fn paging_framebuffer(
+    os: &impl Os,
+    page_phys: usize,
+    framebuffer_phys: u64,
+    framebuffer_size: u64,
+) -> Option<u64> {
+    unsafe {
+        if crate::KERNEL_64BIT {
+            x64::paging_framebuffer(os, page_phys, framebuffer_phys, framebuffer_size)
+        } else {
+            x32::paging_framebuffer(os, page_phys, framebuffer_phys, framebuffer_size)
+        }
+    }
+}

src/arch/x86/x32.rs

@@ -0,0 +1,88 @@
+use crate::area_add;
+use crate::os::{Os, OsMemoryEntry, OsMemoryKind};
+use core::slice;
+
+const PAGE_ENTRIES: usize = 1024;
+const PAGE_SIZE: usize = 4096;
+pub(crate) const PHYS_OFFSET: u32 = 0x8000_0000;
+
+unsafe fn paging_allocate(os: &impl Os) -> Option<&'static mut [u32]> {
+    unsafe {
+        let ptr = os.alloc_zeroed_page_aligned(PAGE_SIZE);
+        if !ptr.is_null() {
+            area_add(OsMemoryEntry {
+                base: ptr as u64,
+                size: PAGE_SIZE as u64,
+                kind: OsMemoryKind::Reclaim,
+            });
+            Some(slice::from_raw_parts_mut(ptr as *mut u32, PAGE_ENTRIES))
+        } else {
+            None
+        }
+    }
+}
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        let pd = paging_allocate(os)?;
+        //Identity map 1 GiB using 4 MiB pages, also map at PHYS_OFFSET
+        for pd_i in 0..256 {
+            let addr = pd_i as u32 * 0x40_0000;
+            pd[pd_i] = addr | 1 << 7 | 1 << 1 | 1;
+            pd[pd_i + 512] = addr | 1 << 7 | 1 << 1 | 1;
+        }
+
+        // Map kernel_size at kernel offset
+        let mut kernel_mapped = 0;
+        let mut pd_i = 0xC000_0000 / 0x40_0000;
+        while kernel_mapped < kernel_size && pd_i < pd.len() {
+            let pt = paging_allocate(os)?;
+            pd[pd_i] = pt.as_ptr() as u32 | 1 << 1 | 1;
+            pd_i += 1;
+
+            let mut pt_i = 0;
+            while kernel_mapped < kernel_size && pt_i < pt.len() {
+                let addr = kernel_phys + kernel_mapped;
+                pt[pt_i] = addr as u32 | 1 << 1 | 1;
+                pt_i += 1;
+                kernel_mapped += PAGE_SIZE as u64;
+            }
+        }
+        assert!(kernel_mapped >= kernel_size);
+
+        Some(pd.as_ptr() as usize)
+    }
+}
+
+pub unsafe fn paging_framebuffer(
+    os: &impl Os,
+    page_phys: usize,
+    framebuffer_phys: u64,
+    framebuffer_size: u64,
+) -> Option<u64> {
+    unsafe {
+        let framebuffer_virt = 0xD000_0000; // 256 MiB after kernel mapping, but before heap mapping
+
+        let pd = slice::from_raw_parts_mut(page_phys as *mut u32, PAGE_ENTRIES);
+
+        // Map framebuffer_size at framebuffer offset
+        let mut framebuffer_mapped = 0;
+        let mut pd_i = framebuffer_virt / 0x40_0000;
+        while framebuffer_mapped < framebuffer_size && pd_i < pd.len() {
+            let pt = paging_allocate(os)?;
+            pd[pd_i] = pt.as_ptr() as u32 | 1 << 1 | 1;
+            pd_i += 1;
+
+            let mut pt_i = 0;
+            while framebuffer_mapped < framebuffer_size && pt_i < pt.len() {
+                let addr = framebuffer_phys + framebuffer_mapped;
+                pt[pt_i] = addr as u32 | 1 << 1 | 1;
+                pt_i += 1;
+                framebuffer_mapped += PAGE_SIZE as u64;
+            }
+        }
+        assert!(framebuffer_mapped >= framebuffer_size);
+
+        Some(framebuffer_virt as u64)
+    }
+}

src/arch/x86/x64.rs

@@ -0,0 +1,148 @@
+use core::slice;
+
+use crate::area_add;
+use crate::os::{Os, OsMemoryEntry, OsMemoryKind};
+
+const ENTRY_ADDRESS_MASK: u64 = 0x000F_FFFF_FFFF_F000;
+const PAGE_ENTRIES: usize = 512;
+const PAGE_SIZE: usize = 4096;
+pub(crate) const PHYS_OFFSET: u64 = 0xFFFF_8000_0000_0000;
+
+unsafe fn paging_allocate(os: &impl Os) -> Option<&'static mut [u64]> {
+    unsafe {
+        let ptr = os.alloc_zeroed_page_aligned(PAGE_SIZE);
+        if !ptr.is_null() {
+            area_add(OsMemoryEntry {
+                base: ptr as u64,
+                size: PAGE_SIZE as u64,
+                kind: OsMemoryKind::Reclaim,
+            });
+
+            Some(slice::from_raw_parts_mut(ptr as *mut u64, PAGE_ENTRIES))
+        } else {
+            None
+        }
+    }
+}
+
+const PRESENT: u64 = 1;
+const WRITABLE: u64 = 1 << 1;
+const LARGE: u64 = 1 << 7;
+
+pub unsafe fn paging_create(os: &impl Os, kernel_phys: u64, kernel_size: u64) -> Option<usize> {
+    unsafe {
+        // Create PML4
+        let pml4 = paging_allocate(os)?;
+
+        {
+            // Create PDP for identity mapping
+            let pdp = paging_allocate(os)?;
+
+            // Link first user and first kernel PML4 entry to PDP
+            pml4[0] = pdp.as_ptr() as u64 | WRITABLE | PRESENT;
+            pml4[256] = pdp.as_ptr() as u64 | WRITABLE | PRESENT;
+
+            // Identity map 8 GiB using 2 MiB pages
+            for pdp_i in 0..8 {
+                let pd = paging_allocate(os)?;
+                pdp[pdp_i] = pd.as_ptr() as u64 | WRITABLE | PRESENT;
+                for pd_i in 0..pd.len() {
+                    let addr = pdp_i as u64 * 0x4000_0000 + pd_i as u64 * 0x20_0000;
+                    pd[pd_i] = addr | LARGE | WRITABLE | PRESENT;
+                }
+            }
+        }
+
+        {
+            // Create PDP (spanning 512 GiB) for kernel mapping
+            let pdp = paging_allocate(os)?;
+
+            // Link last PML4 entry to PDP
+            pml4[511] = pdp.as_ptr() as u64 | WRITABLE | PRESENT;
+
+            // Create PD (spanning 1 GiB) for kernel mapping.
+            let pd = paging_allocate(os)?;
+
+            // The kernel is mapped at -2^31, i.e. 0xFFFF_FFFF_8000_0000. Since a PD is 1 GiB, link
+            // the second last PDP entry to PD.
+            pdp[510] = pd.as_ptr() as u64 | WRITABLE | PRESENT;
+
+            // Map kernel_size bytes to kernel offset, i.e. to the start of the PD.
+
+            let mut kernel_mapped = 0;
+
+            let mut pd_idx = 0;
+            while kernel_mapped < kernel_size && pd_idx < pd.len() {
+                let pt = paging_allocate(os)?;
+                pd[pd_idx] = pt.as_ptr() as u64 | WRITABLE | PRESENT;
+                pd_idx += 1;
+
+                let mut pt_idx = 0;
+                while kernel_mapped < kernel_size && pt_idx < pt.len() {
+                    let addr = kernel_phys + kernel_mapped;
+                    pt[pt_idx] = addr | WRITABLE | PRESENT;
+                    pt_idx += 1;
+                    kernel_mapped += PAGE_SIZE as u64;
+                }
+            }
+            assert!(kernel_mapped >= kernel_size);
+        }
+
+        Some(pml4.as_ptr() as usize)
+    }
+}
+
+pub unsafe fn paging_framebuffer(
+    os: &impl Os,
+    page_phys: usize,
+    framebuffer_phys: u64,
+    framebuffer_size: u64,
+) -> Option<u64> {
+    unsafe {
+        //TODO: smarter test for framebuffer already mapped
+        if framebuffer_phys + framebuffer_size <= 0x2_0000_0000 {
+            return Some(framebuffer_phys + PHYS_OFFSET);
+        }
+
+        let pml4_i = ((framebuffer_phys / 0x80_0000_0000) + 256) as usize;
+        let mut pdp_i = ((framebuffer_phys % 0x80_0000_0000) / 0x4000_0000) as usize;
+        let mut pd_i = ((framebuffer_phys % 0x4000_0000) / 0x20_0000) as usize;
+        assert_eq!(framebuffer_phys % 0x20_0000, 0);
+
+        let pml4 = slice::from_raw_parts_mut(page_phys as *mut u64, PAGE_ENTRIES);
+
+        // Create PDP for framebuffer mapping
+        let pdp = if pml4[pml4_i] == 0 {
+            let pdp = paging_allocate(os)?;
+            pml4[pml4_i] = pdp.as_ptr() as u64 | 1 << 1 | 1;
+            pdp
+        } else {
+            slice::from_raw_parts_mut(
+                (pml4[pml4_i] & ENTRY_ADDRESS_MASK) as *mut u64,
+                PAGE_ENTRIES,
+            )
+        };
+
+        // Map framebuffer_size at framebuffer offset
+        let mut framebuffer_mapped = 0;
+        while framebuffer_mapped < framebuffer_size && pdp_i < pdp.len() {
+            let pd = paging_allocate(os)?;
+            assert_eq!(pdp[pdp_i], 0);
+            pdp[pdp_i] = pd.as_ptr() as u64 | 1 << 1 | 1;
+
+            while framebuffer_mapped < framebuffer_size && pd_i < pd.len() {
+                let addr = framebuffer_phys + framebuffer_mapped;
+                assert_eq!(pd[pd_i], 0);
+                pd[pd_i] = addr | 1 << 7 | 1 << 1 | 1;
+                framebuffer_mapped += 0x20_0000;
+                pd_i += 1;
+            }
+
+            pdp_i += 1;
+            pd_i = 0;
+        }
+        assert!(framebuffer_mapped >= framebuffer_size);
+
+        Some(framebuffer_phys + PHYS_OFFSET)
+    }
+}

src/editor.rs

@@ -0,0 +1,121 @@
+use crate::os::{Os, OsKey};
+
+fn edit_banner(os: &impl Os) {
+    os.clear_text();
+    println!("--- Redox Bootloader Environment Editor ---");
+    println!("ENTER twice to boot. UP/DOWN to edit lines.");
+    println!("-------------------------------------------");
+}
+
+pub fn edit_env(os: &impl Os, env_ptr: *mut u8, env_size: &mut usize, max_size: usize) {
+    edit_banner(os);
+
+    let env_slice = unsafe { core::slice::from_raw_parts_mut(env_ptr, max_size) };
+    // counting at line index
+    let mut cursor = 0xFFF;
+    // position at current line, not including LF
+    let mut cursor_start = 0;
+    let mut cursor_end = 0;
+    let original_size = *env_size;
+
+    loop {
+        os.set_text_position(0, 4);
+
+        let mut iline = 0;
+        for i in 0..*env_size {
+            let c = env_slice[i] as char;
+            if c == '\n' {
+                os.set_text_highlight(iline == cursor);
+                print!(" ");
+                os.set_text_highlight(false);
+                print!("\n");
+                iline += 1;
+                if iline == cursor {
+                    cursor_start = i + 1;
+                }
+            } else {
+                print!("{}", c);
+            }
+            if iline == cursor {
+                cursor_end = i + 1;
+            }
+        }
+        if cursor > iline {
+            cursor = iline;
+            // update cursors, should never hang
+            continue;
+        }
+        os.set_text_highlight(iline == cursor);
+        print!(" ");
+        os.set_text_highlight(false);
+
+        match os.get_key() {
+            OsKey::Enter => {
+                if cursor_start == cursor_end {
+                    // blank line to boot
+                    break;
+                }
+
+                if *env_size < max_size - 1 {
+                    if *env_size == max_size {
+                        continue;
+                    }
+                    for i in (cursor_end..*env_size).rev() {
+                        env_slice[i + 1] = env_slice[i];
+                    }
+                    env_slice[cursor_end] = b'\n';
+                    *env_size += 1;
+                    cursor += 1;
+                    edit_banner(os);
+                }
+            }
+            OsKey::Backspace => {
+                if cursor_end == 0 || *env_size == 0 {
+                    continue;
+                }
+                if cursor_start == cursor_end && iline > 0 {
+                    iline -= 1;
+                }
+                for i in cursor_end..*env_size {
+                    env_slice[i - 1] = env_slice[i];
+                }
+                *env_size -= 1;
+                edit_banner(os);
+            }
+            OsKey::Up => {
+                if cursor > 0 {
+                    cursor -= 1;
+                }
+            }
+            OsKey::Down => {
+                cursor += 1;
+            }
+            OsKey::Char(c) => {
+                if *env_size == max_size {
+                    continue;
+                }
+                for i in (cursor_end..*env_size).rev() {
+                    env_slice[i + 1] = env_slice[i];
+                }
+                env_slice[cursor_end] = c as u8;
+                *env_size += 1;
+            }
+            _ => (),
+        }
+    }
+
+    if *env_size == 0 || env_slice[*env_size - 1] != b'\n' {
+        if *env_size < max_size {
+            env_slice[*env_size] = b'\n';
+            *env_size += 1;
+        }
+    }
+
+    if *env_size < original_size {
+        for i in (*env_size..original_size).rev() {
+            env_slice[i] = 0;
+        }
+    }
+
+    println!("\nBooting...");
+}

src/logger.rs

@@ -0,0 +1,26 @@
+use log::{LevelFilter, Log, Metadata, Record};
+
+pub static LOGGER: Logger = Logger;
+
+pub struct Logger;
+
+impl Logger {
+    pub fn init(&'static self) {
+        log::set_logger(self).unwrap();
+        log::set_max_level(LevelFilter::Info);
+    }
+}
+
+impl Log for Logger {
+    fn enabled(&self, _metadata: &Metadata) -> bool {
+        true
+    }
+
+    fn log(&self, record: &Record) {
+        if self.enabled(record.metadata()) {
+            println!("{} - {}", record.level(), record.args());
+        }
+    }
+
+    fn flush(&self) {}
+}

src/main.rs

@@ -0,0 +1,675 @@
+#![no_std]
+#![cfg_attr(any(target_arch = "riscv64", target_os = "uefi"), no_main)]
+
+extern crate alloc;
+
+#[cfg(any(target_arch = "riscv64", target_os = "uefi"))]
+#[macro_use]
+extern crate uefi_std as std;
+
+use alloc::{format, string::String, vec::Vec};
+use core::{
+    cmp,
+    fmt::{self, Write},
+    mem, ptr, slice, str,
+};
+use redoxfs::{Disk, Node, TreeData};
+
+use self::arch::{paging_create, paging_framebuffer};
+use self::os::{Os, OsHwDesc, OsKey, OsMemoryEntry, OsMemoryKind, OsVideoMode};
+
+#[macro_use]
+mod os;
+
+mod arch;
+mod editor;
+mod logger;
+mod serial_16550;
+
+const KIBI: usize = 1024;
+const MIBI: usize = KIBI * KIBI;
+
+//TODO: allocate this in a more reasonable manner
+static mut AREAS: [OsMemoryEntry; 1024] = [OsMemoryEntry {
+    base: 0,
+    size: 0,
+    kind: OsMemoryKind::Null,
+}; 1024];
+static mut AREAS_LEN: usize = 0;
+
+pub fn area_add(area: OsMemoryEntry) {
+    #[allow(static_mut_refs)]
+    unsafe {
+        for existing_area in &mut AREAS[0..AREAS_LEN] {
+            if existing_area.kind == area.kind {
+                if existing_area.base.unchecked_add(existing_area.size) == area.base {
+                    existing_area.size += area.size;
+                    return;
+                }
+                if area.base.unchecked_add(area.size) == existing_area.base {
+                    existing_area.size += area.size;
+                    existing_area.base = area.base;
+                    return;
+                }
+            }
+        }
+        *AREAS.get_mut(AREAS_LEN).expect("AREAS overflowed!") = area;
+        AREAS_LEN += 1;
+    }
+}
+
+pub static mut KERNEL_64BIT: bool = false;
+
+pub static mut LIVE_OPT: Option<(u64, &'static [u8])> = None;
+
+struct SliceWriter<'a> {
+    slice: &'a mut [u8],
+    i: usize,
+}
+
+impl<'a> Write for SliceWriter<'a> {
+    fn write_str(&mut self, s: &str) -> fmt::Result {
+        for b in s.bytes() {
+            if let Some(slice_b) = self.slice.get_mut(self.i) {
+                *slice_b = b;
+                self.i += 1;
+            } else {
+                return Err(fmt::Error);
+            }
+        }
+        Ok(())
+    }
+}
+
+#[allow(dead_code)]
+#[derive(Debug)]
+#[repr(C, packed(8))]
+pub struct KernelArgs {
+    kernel_base: u64,
+    kernel_size: u64,
+    stack_base: u64,
+    stack_size: u64,
+    env_base: u64,
+    env_size: u64,
+
+    /// The base pointer to the saved RSDP.
+    ///
+    /// This field can be NULL, and if so, the system has not booted with UEFI or in some other way
+    /// retrieved the RSDPs. The kernel or a userspace driver will thus try searching the BIOS
+    /// memory instead. On UEFI systems, searching is not guaranteed to actually work though.
+    acpi_rsdp_base: u64,
+    /// The size of the RSDP region.
+    acpi_rsdp_size: u64,
+
+    areas_base: u64,
+    areas_size: u64,
+
+    bootstrap_base: u64,
+    bootstrap_size: u64,
+}
+
+fn select_mode(
+    os: &impl Os,
+    output_i: usize,
+    live: &mut bool,
+    edit_env: &mut bool,
+) -> Option<OsVideoMode> {
+    let mut modes = Vec::new();
+    for mode in os.video_modes(output_i) {
+        let mut aspect_w = mode.width;
+        let mut aspect_h = mode.height;
+        for i in 2..cmp::min(aspect_w / 2, aspect_h / 2) {
+            while aspect_w % i == 0 && aspect_h % i == 0 {
+                aspect_w /= i;
+                aspect_h /= i;
+            }
+        }
+
+        modes.push((
+            mode,
+            format!(
+                "{:>4}x{:<4} {:>3}:{:<3}",
+                mode.width, mode.height, aspect_w, aspect_h
+            ),
+        ));
+    }
+
+    if modes.is_empty() {
+        return None;
+    }
+
+    // Sort modes by pixel area, reversed
+    modes.sort_by(|a, b| (b.0.width * b.0.height).cmp(&(a.0.width * a.0.height)));
+
+    // Set selected based on best resolution
+    print!("Output {}", output_i);
+    let mut selected = modes.first().map_or(0, |x| x.0.id);
+    if let Some((best_width, best_height)) = os.best_resolution(output_i) {
+        print!(", best resolution: {}x{}", best_width, best_height);
+        for (mode, _text) in modes.iter() {
+            if mode.width == best_width && mode.height == best_height {
+                selected = mode.id;
+                break;
+            }
+        }
+    }
+    println!();
+
+    println!("Arrow keys and enter select mode");
+    let live_mode = os.get_text_position();
+    if *live {
+        println!("Press l to disable live mode");
+    } else {
+        println!("Press l to  enable live mode");
+    }
+    println!("Press e to edit boot environment");
+    println!();
+    print!(" ");
+
+    let (off_x, off_y) = os.get_text_position();
+    let rows = 12;
+    let mut mode_opt = None;
+    while !modes.is_empty() {
+        let mut row = 0;
+        let mut col = 0;
+        for (mode, text) in modes.iter() {
+            if row >= rows {
+                col += 1;
+                row = 0;
+            }
+
+            os.set_text_position(off_x + col * 20, off_y + row);
+            os.set_text_highlight(mode.id == selected);
+
+            print!("{}", text);
+
+            row += 1;
+        }
+
+        // Read keypress
+        match os.get_key() {
+            OsKey::Left => {
+                if let Some(mut mode_i) = modes.iter().position(|x| x.0.id == selected) {
+                    if mode_i < rows {
+                        while mode_i < modes.len() {
+                            mode_i += rows;
+                        }
+                    }
+                    mode_i -= rows;
+                    if let Some(new) = modes.get(mode_i) {
+                        selected = new.0.id;
+                    }
+                }
+            }
+            OsKey::Right => {
+                if let Some(mut mode_i) = modes.iter().position(|x| x.0.id == selected) {
+                    mode_i += rows;
+                    if mode_i >= modes.len() {
+                        mode_i %= rows;
+                    }
+                    if let Some(new) = modes.get(mode_i) {
+                        selected = new.0.id;
+                    }
+                }
+            }
+            OsKey::Up => {
+                if let Some(mut mode_i) = modes.iter().position(|x| x.0.id == selected) {
+                    if mode_i % rows == 0 {
+                        mode_i += rows;
+                        if mode_i > modes.len() {
+                            mode_i = modes.len();
+                        }
+                    }
+                    mode_i -= 1;
+                    if let Some(new) = modes.get(mode_i) {
+                        selected = new.0.id;
+                    }
+                }
+            }
+            OsKey::Down => {
+                if let Some(mut mode_i) = modes.iter().position(|x| x.0.id == selected) {
+                    mode_i += 1;
+                    if mode_i % rows == 0 {
+                        mode_i -= rows;
+                    }
+                    if mode_i >= modes.len() {
+                        mode_i = mode_i - mode_i % rows;
+                    }
+                    if let Some(new) = modes.get(mode_i) {
+                        selected = new.0.id;
+                    }
+                }
+            }
+            OsKey::Enter => {
+                if let Some(mode_i) = modes.iter().position(|x| x.0.id == selected) {
+                    if let Some((mode, _text)) = modes.get(mode_i) {
+                        mode_opt = Some(*mode);
+                    }
+                }
+                break;
+            }
+            OsKey::Char('l') => {
+                *live = !*live;
+                os.set_text_position(live_mode.0, live_mode.1);
+                if *live {
+                    println!("Press l to disable live mode");
+                } else {
+                    println!("Press l to  enable live mode");
+                }
+            }
+            OsKey::Char('e') => {
+                if let Some(mode_i) = modes.iter().position(|x| x.0.id == selected) {
+                    if let Some((mode, _text)) = modes.get(mode_i) {
+                        *edit_env = true;
+                        mode_opt = Some(*mode);
+                    }
+                }
+                break;
+            }
+            _ => (),
+        }
+    }
+
+    os.set_text_position(0, off_y + rows);
+    os.set_text_highlight(false);
+    println!();
+
+    mode_opt
+}
+
+fn redoxfs<O: Os>(os: &O) -> (redoxfs::FileSystem<O::D>, Option<&'static [u8]>) {
+    let attempts = 10;
+    for attempt in 0..=attempts {
+        let mut password_opt = None;
+        if attempt > 0 {
+            print!("\rRedoxFS password ({}/{}): ", attempt, attempts);
+
+            let mut password = String::new();
+
+            loop {
+                match os.get_key() {
+                    OsKey::Backspace | OsKey::Delete => {
+                        if !password.is_empty() {
+                            print!("\x08 \x08");
+                            password.pop();
+                        }
+                    }
+                    OsKey::Char(c) => {
+                        print!("*");
+                        password.push(c)
+                    }
+                    OsKey::Enter => break,
+                    _ => (),
+                }
+            }
+
+            // Erase password information
+            while os.get_text_position().0 > 0 {
+                print!("\x08 \x08");
+            }
+
+            if !password.is_empty() {
+                password_opt = Some(password);
+            }
+        }
+        match os.filesystem(password_opt.as_ref().map(|x| x.as_bytes())) {
+            Ok(fs) => {
+                return (
+                    fs,
+                    password_opt.map(|password| {
+                        // Copy password to page aligned memory
+                        let password_size = password.len();
+                        let password_base = os.alloc_zeroed_page_aligned(password_size);
+
+                        area_add(OsMemoryEntry {
+                            base: password_base as u64,
+                            size: password_size as u64,
+                            kind: OsMemoryKind::Reserved,
+                        });
+
+                        unsafe {
+                            ptr::copy(password.as_ptr(), password_base, password_size);
+                            slice::from_raw_parts(password_base, password_size)
+                        }
+                    }),
+                );
+            }
+            Err(err) => match err.errno {
+                // Incorrect password, try again
+                syscall::ENOKEY => (),
+                _ => {
+                    panic!("Failed to open RedoxFS: {}", err);
+                }
+            },
+        }
+    }
+    panic!("RedoxFS out of unlock attempts");
+}
+
+#[derive(PartialEq)]
+enum Filetype {
+    Elf,
+    Initfs,
+}
+fn load_to_memory<O: Os>(
+    os: &O,
+    fs: &mut redoxfs::FileSystem<O::D>,
+    path: &str,
+    filetype: Filetype,
+) -> &'static mut [u8] {
+    fs.tx(|tx| {
+        let mut node = None;
+        for component in path.split('/') {
+            node = Some(
+                tx.find_node(
+                    node.map_or(redoxfs::TreePtr::root(), |node: TreeData<Node>| node.ptr()),
+                    component,
+                )
+                .unwrap_or_else(|err| panic!("Failed to find {component}: {err}")),
+            );
+        }
+        let node = node.unwrap();
+
+        let size = node.data().size();
+
+        print!("{}: 0/{} MiB", path, size / MIBI as u64);
+
+        let ptr = os.alloc_zeroed_page_aligned(size as usize);
+        if ptr.is_null() {
+            panic!("Failed to allocate memory for {}", path);
+        }
+
+        let slice = unsafe { slice::from_raw_parts_mut(ptr, size as usize) };
+
+        let mut i = 0;
+        for chunk in slice.chunks_mut(MIBI) {
+            print!("\r{}: {}/{} MiB", path, i / MIBI as u64, size / MIBI as u64);
+            i += tx
+                .read_node_inner(&node, i, chunk)
+                .unwrap_or_else(|err| panic!("Failed to read `{}` file: {}", path, err))
+                as u64;
+        }
+        println!("\r{}: {}/{} MiB", path, i / MIBI as u64, size / MIBI as u64);
+
+        if filetype == Filetype::Elf {
+            let magic = &slice[..4];
+            if magic != b"\x7FELF" {
+                panic!("{} has invalid magic number {:#X?}", path, magic);
+            }
+        } else if filetype == Filetype::Initfs {
+            let magic = &slice[..8];
+            if magic != b"RedoxFtw" {
+                panic!("{} has invalid magic number {:#X?}", path, magic);
+            }
+        }
+
+        Ok(slice)
+    })
+    .unwrap_or_else(|err| {
+        panic!(
+            "RedoxFS transaction failed while loading `{}`: {}",
+            path, err
+        )
+    })
+}
+
+fn elf_entry(data: &[u8]) -> (u64, bool) {
+    match (data[4], data[5]) {
+        // 32-bit, little endian
+        (1, 1) => (
+            u32::from_le_bytes(
+                <[u8; 4]>::try_from(&data[0x18..0x18 + 4]).expect("conversion cannot fail"),
+            ) as u64,
+            false,
+        ),
+        // 32-bit, big endian
+        (1, 2) => (
+            u32::from_be_bytes(
+                <[u8; 4]>::try_from(&data[0x18..0x18 + 4]).expect("conversion cannot fail"),
+            ) as u64,
+            false,
+        ),
+        // 64-bit, little endian
+        (2, 1) => (
+            u64::from_le_bytes(
+                <[u8; 8]>::try_from(&data[0x18..0x18 + 8]).expect("conversion cannot fail"),
+            ),
+            true,
+        ),
+        // 64-bit, big endian
+        (2, 2) => (
+            u64::from_be_bytes(
+                <[u8; 8]>::try_from(&data[0x18..0x18 + 8]).expect("conversion cannot fail"),
+            ),
+            true,
+        ),
+        (ei_class, ei_data) => {
+            panic!("Unsupported ELF EI_CLASS {} EI_DATA {}", ei_class, ei_data);
+        }
+    }
+}
+
+fn main(os: &impl Os) -> (usize, u64, KernelArgs) {
+    println!(
+        "Redox OS Bootloader {} on {}",
+        env!("CARGO_PKG_VERSION"),
+        os.name()
+    );
+
+    let hwdesc = os.hwdesc();
+    println!("Hardware descriptor: {:x?}", hwdesc);
+    let (acpi_rsdp_base, acpi_rsdp_size) = match hwdesc {
+        OsHwDesc::Acpi(base, size) => (base, size),
+        OsHwDesc::DeviceTree(base, size) => (base, size),
+        OsHwDesc::NotFound => (0, 0),
+    };
+
+    let (mut fs, password_opt) = redoxfs(os);
+
+    print!("RedoxFS ");
+    for i in 0..fs.header.uuid().len() {
+        if i == 4 || i == 6 || i == 8 || i == 10 {
+            print!("-");
+        }
+
+        print!("{:>02x}", fs.header.uuid()[i]);
+    }
+    println!(": {} MiB", fs.header.size() / MIBI as u64);
+    println!();
+
+    let mut mode_opts = Vec::new();
+    let mut live = cfg!(feature = "live");
+    let mut edit_env = false;
+    for output_i in 0..os.video_outputs() {
+        if output_i > 0 {
+            os.clear_text();
+        }
+        mode_opts.push(select_mode(os, output_i, &mut live, &mut edit_env));
+    }
+
+    let stack_size = 128 * KIBI;
+    let stack_base = os.alloc_zeroed_page_aligned(stack_size);
+    if stack_base.is_null() {
+        panic!("Failed to allocate memory for stack");
+    }
+
+    let live_opt = if live {
+        let size = fs.header.size();
+
+        print!("live: 0/{} MiB", size / MIBI as u64);
+
+        let ptr = os.alloc_zeroed_page_aligned(size as usize);
+        if ptr.is_null() {
+            panic!("Failed to allocate memory for live");
+        }
+
+        let live = unsafe { slice::from_raw_parts_mut(ptr, size as usize) };
+
+        let mut i = 0;
+        for chunk in live.chunks_mut(MIBI) {
+            print!("\rlive: {}/{} MiB", i / MIBI as u64, size / MIBI as u64);
+            i += unsafe {
+                fs.disk
+                    .read_at(fs.block + i / redoxfs::BLOCK_SIZE, chunk)
+                    .expect("Failed to read live disk") as u64
+            };
+        }
+        println!("\rlive: {}/{} MiB", i / MIBI as u64, size / MIBI as u64);
+
+        println!("Switching to live disk");
+        unsafe {
+            LIVE_OPT = Some((fs.block, slice::from_raw_parts_mut(ptr, size as usize)));
+        }
+
+        area_add(OsMemoryEntry {
+            base: live.as_ptr() as u64,
+            size: live.len() as u64,
+            kind: OsMemoryKind::Reserved,
+        });
+
+        Some(live)
+    } else {
+        None
+    };
+
+    let (kernel, kernel_entry) = {
+        let kernel = load_to_memory(os, &mut fs, "usr/lib/boot/kernel", Filetype::Elf);
+        let (kernel_entry, kernel_64bit) = elf_entry(kernel);
+        unsafe {
+            KERNEL_64BIT = kernel_64bit;
+        }
+        (kernel, kernel_entry)
+    };
+
+    let (bootstrap_size, bootstrap_base) = {
+        let initfs_slice = load_to_memory(os, &mut fs, "usr/lib/boot/initfs", Filetype::Initfs);
+
+        let memory = unsafe {
+            let total_size = initfs_slice.len().next_multiple_of(4096);
+            let ptr = os.alloc_zeroed_page_aligned(total_size);
+            assert!(!ptr.is_null(), "failed to allocate bootstrap+initfs memory");
+            core::slice::from_raw_parts_mut(ptr, total_size)
+        };
+        memory[..initfs_slice.len()].copy_from_slice(initfs_slice);
+
+        (memory.len() as u64, memory.as_mut_ptr() as u64)
+    };
+
+    let page_phys = unsafe { paging_create(os, kernel.as_ptr() as u64, kernel.len() as u64) }
+        .expect("Failed to set up paging");
+
+    let max_env_size = 64 * KIBI;
+    let mut env_size = max_env_size;
+    let env_base = os.alloc_zeroed_page_aligned(env_size);
+    if env_base.is_null() {
+        panic!("Failed to allocate memory for stack");
+    }
+
+    {
+        let mut w = SliceWriter {
+            slice: unsafe { slice::from_raw_parts_mut(env_base, max_env_size) },
+            i: 0,
+        };
+
+        match hwdesc {
+            OsHwDesc::Acpi(addr, size) => {
+                writeln!(w, "RSDP_ADDR={addr:016x}").unwrap();
+                writeln!(w, "RSDP_SIZE={size:016x}").unwrap();
+            }
+            OsHwDesc::DeviceTree(addr, size) => {
+                writeln!(w, "DTB_ADDR={addr:016x}").unwrap();
+                writeln!(w, "DTB_SIZE={size:016x}").unwrap();
+            }
+            OsHwDesc::NotFound => {}
+        }
+
+        if let Some(live) = live_opt {
+            writeln!(w, "DISK_LIVE_ADDR={:016x}", live.as_ptr() as usize).unwrap();
+            writeln!(w, "DISK_LIVE_SIZE={:016x}", live.len()).unwrap();
+            writeln!(w, "REDOXFS_BLOCK={:016x}", 0).unwrap();
+        } else {
+            writeln!(w, "REDOXFS_BLOCK={:016x}", fs.block).unwrap();
+        }
+        write!(w, "REDOXFS_UUID=").unwrap();
+        for i in 0..fs.header.uuid().len() {
+            if i == 4 || i == 6 || i == 8 || i == 10 {
+                write!(w, "-").unwrap();
+            }
+
+            write!(w, "{:>02x}", fs.header.uuid()[i]).unwrap();
+        }
+        writeln!(w).unwrap();
+        if let Some(password) = password_opt {
+            writeln!(
+                w,
+                "REDOXFS_PASSWORD_ADDR={:016x}",
+                password.as_ptr() as usize
+            )
+            .unwrap();
+            writeln!(w, "REDOXFS_PASSWORD_SIZE={:016x}", password.len()).unwrap();
+        }
+
+        #[cfg(target_arch = "riscv64")]
+        {
+            let boot_hartid = os::efi_get_boot_hartid()
+                .expect("Could not retrieve boot hart id from EFI implementation!");
+            writeln!(w, "BOOT_HART_ID={:016x}", boot_hartid).unwrap();
+        }
+        if edit_env {
+            editor::edit_env(os, env_base, &mut w.i, max_env_size);
+        }
+
+        for output_i in 0..os.video_outputs() {
+            if let Some(mut mode) = mode_opts[output_i] {
+                // Set mode to get updated values
+                os.set_video_mode(output_i, &mut mode);
+
+                if output_i == 0 {
+                    let virt = unsafe {
+                        paging_framebuffer(
+                            os,
+                            page_phys,
+                            mode.base,
+                            (mode.stride * mode.height * 4) as u64,
+                        )
+                    }
+                    .expect("Failed to map framebuffer");
+
+                    writeln!(w, "FRAMEBUFFER_ADDR={:016x}", mode.base).unwrap();
+                    writeln!(w, "FRAMEBUFFER_VIRT={virt:016x}").unwrap();
+                    writeln!(w, "FRAMEBUFFER_WIDTH={:016x}", mode.width).unwrap();
+                    writeln!(w, "FRAMEBUFFER_HEIGHT={:016x}", mode.height).unwrap();
+                    writeln!(w, "FRAMEBUFFER_STRIDE={:016x}", mode.stride).unwrap();
+                } else {
+                    writeln!(
+                        w,
+                        "FRAMEBUFFER{}={:#x},{},{},{}",
+                        output_i, mode.base, mode.width, mode.height, mode.stride,
+                    )
+                    .unwrap();
+                }
+            }
+        }
+        env_size = w.i;
+    }
+
+    #[allow(static_mut_refs)]
+    (
+        page_phys,
+        kernel_entry,
+        KernelArgs {
+            kernel_base: kernel.as_ptr() as u64,
+            kernel_size: kernel.len() as u64,
+            stack_base: stack_base as u64,
+            stack_size: stack_size as u64,
+            env_base: env_base as u64,
+            env_size: env_size as u64,
+            acpi_rsdp_base,
+            acpi_rsdp_size,
+            areas_base: unsafe { AREAS.as_ptr() as u64 },
+            areas_size: unsafe { (AREAS.len() * mem::size_of::<OsMemoryEntry>()) as u64 },
+            bootstrap_base,
+            bootstrap_size,
+        },
+    )
+}

src/os/bios/disk.rs

@@ -0,0 +1,177 @@
+use core::{mem, ptr};
+use redoxfs::{BLOCK_SIZE, Disk};
+use syscall::error::{EIO, Error, Result};
+
+use super::{DISK_ADDRESS_PACKET_ADDR, DISK_BIOS_ADDR, ThunkData};
+
+const SECTOR_SIZE: u64 = 512;
+const BLOCKS_PER_SECTOR: u64 = BLOCK_SIZE / SECTOR_SIZE;
+// 128 sectors is the amount allocated for DISK_BIOS_ADDR
+// 127 sectors is the maximum for many BIOSes
+const MAX_SECTORS: u64 = 127;
+const MAX_BLOCKS: u64 = MAX_SECTORS * SECTOR_SIZE / BLOCK_SIZE;
+
+#[allow(dead_code)]
+#[derive(Clone, Copy)]
+#[repr(C, packed)]
+pub struct DiskAddressPacket {
+    size: u8,
+    reserved: u8,
+    sectors: u16,
+    buffer: u16,
+    segment: u16,
+    address: u64,
+}
+
+impl DiskAddressPacket {
+    pub fn from_block(block: u64, count: u64) -> DiskAddressPacket {
+        let address = block * BLOCKS_PER_SECTOR;
+        let sectors = count * BLOCKS_PER_SECTOR;
+        assert!(sectors <= MAX_SECTORS);
+        DiskAddressPacket {
+            size: mem::size_of::<DiskAddressPacket>() as u8,
+            reserved: 0,
+            sectors: sectors as u16,
+            buffer: (DISK_BIOS_ADDR & 0xF) as u16,
+            segment: (DISK_BIOS_ADDR >> 4) as u16,
+            address,
+        }
+    }
+}
+
+pub struct DiskBios {
+    boot_disk: u8,
+    thunk13: extern "C" fn(),
+    chs_opt: Option<(u32, u32, u32)>,
+}
+
+impl DiskBios {
+    pub fn new(boot_disk: u8, thunk13: extern "C" fn()) -> Self {
+        let chs_opt = unsafe {
+            let mut data = ThunkData::new();
+            data.eax = 0x4100;
+            data.ebx = 0x55AA;
+            data.edx = boot_disk as u32;
+
+            data.with(thunk13);
+
+            if (data.ebx & 0xFFFF) == 0xAA55 {
+                // Extensions are installed, do not use CHS
+                None
+            } else {
+                // Extensions are not installed, get CHS geometry
+                data = ThunkData::new();
+                data.eax = 0x0800;
+                data.edx = boot_disk as u32;
+                data.edi = 0;
+
+                data.with(thunk13);
+
+                //TODO: return result on error
+                let ah = ({ data.eax } >> 8) & 0xFF;
+                assert_eq!(ah, 0);
+
+                let c = (data.ecx >> 8) & 0xFF | ((data.ecx >> 6) & 0x3) << 8;
+                let h = ((data.edx >> 8) & 0xFF) + 1;
+                let s = data.ecx & 0x3F;
+
+                Some((c, h, s))
+            }
+        };
+
+        Self {
+            boot_disk,
+            thunk13,
+            chs_opt,
+        }
+    }
+}
+
+impl Disk for DiskBios {
+    unsafe fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> Result<usize> {
+        unsafe {
+            // Optimization for live disks
+            if let Some(live) = crate::LIVE_OPT {
+                if block >= live.0 {
+                    let start = ((block - live.0) * BLOCK_SIZE) as usize;
+                    let end = start + buffer.len();
+                    if end <= live.1.len() {
+                        buffer.copy_from_slice(&live.1[start..end]);
+                        return Ok(buffer.len());
+                    }
+                }
+            }
+
+            for (i, chunk) in buffer
+                .chunks_mut((MAX_BLOCKS * BLOCK_SIZE) as usize)
+                .enumerate()
+            {
+                let dap = DiskAddressPacket::from_block(
+                    block + i as u64 * MAX_BLOCKS,
+                    chunk.len() as u64 / BLOCK_SIZE,
+                );
+
+                if let Some((_, h_max, s_max)) = self.chs_opt {
+                    let s = (dap.address % s_max as u64) + 1;
+                    assert!(s <= 63, "invalid sector {s}");
+
+                    let tmp = dap.address / s_max as u64;
+                    let h = tmp % h_max as u64;
+                    assert!(h <= 255, "invalid head {h}");
+
+                    let c = tmp / h_max as u64;
+                    assert!(c <= 1023, "invalid cylinder {c}");
+
+                    let mut data = ThunkData::new();
+                    data.eax = 0x0200 | (dap.sectors as u32);
+                    data.ebx = dap.buffer as u32;
+                    data.ecx =
+                        (s as u32) | (((c as u32) & 0xFF) << 8) | ((((c as u32) >> 8) & 0x3) << 6);
+                    data.edx = (self.boot_disk as u32) | ((h as u32) << 8);
+                    data.es = dap.segment;
+
+                    data.with(self.thunk13);
+
+                    //TODO: return result on error
+                    let ah = ({ data.eax } >> 8) & 0xFF;
+                    assert_eq!(ah, 0);
+                } else {
+                    ptr::write(DISK_ADDRESS_PACKET_ADDR as *mut DiskAddressPacket, dap);
+
+                    let mut data = ThunkData::new();
+                    data.eax = 0x4200;
+                    data.edx = self.boot_disk as u32;
+                    data.esi = DISK_ADDRESS_PACKET_ADDR as u32;
+
+                    data.with(self.thunk13);
+
+                    //TODO: return result on error
+                    let ah = ({ data.eax } >> 8) & 0xFF;
+                    assert_eq!(ah, 0);
+
+                    //TODO: check blocks transferred
+                    // dap = ptr::read(DISK_ADDRESS_PACKET_ADDR as *mut DiskAddressPacket);
+                }
+
+                ptr::copy(DISK_BIOS_ADDR as *const u8, chunk.as_mut_ptr(), chunk.len());
+            }
+
+            Ok(buffer.len())
+        }
+    }
+
+    unsafe fn write_at(&mut self, block: u64, buffer: &[u8]) -> Result<usize> {
+        log::error!(
+            "DiskBios::write_at(0x{:X}, 0x{:X}:0x{:X}) not allowed",
+            block,
+            buffer.as_ptr() as usize,
+            buffer.len()
+        );
+        Err(Error::new(EIO))
+    }
+
+    fn size(&mut self) -> Result<u64> {
+        log::error!("DiskBios::size not implemented");
+        Err(Error::new(EIO))
+    }
+}

src/os/bios/macros.rs

@@ -0,0 +1,20 @@
+/// Print to console
+#[macro_export]
+macro_rules! print {
+    ($($arg:tt)*) => ({
+        use core::fmt::Write;
+        #[cfg(feature = "serial_debug")]
+        {
+            let _ = write!($crate::os::serial::COM1.lock(), $($arg)*);
+        }
+        let _ = write!($crate::os::VGA.lock(), $($arg)*);
+    });
+}
+
+/// Print with new line to console
+#[macro_export]
+macro_rules! println {
+    () => (print!("\n"));
+    ($fmt:expr_2021) => (print!(concat!($fmt, "\n")));
+    ($fmt:expr_2021, $($arg:tt)*) => (print!(concat!($fmt, "\n"), $($arg)*));
+}

src/os/bios/memory_map.rs

@@ -0,0 +1,84 @@
+use core::{cmp, mem, ptr};
+
+use crate::area_add;
+use crate::os::{OsMemoryEntry, OsMemoryKind};
+
+use super::{MEMORY_MAP_ADDR, thunk::ThunkData};
+
+#[repr(C, packed)]
+struct MemoryMapEntry {
+    pub base: u64,
+    pub size: u64,
+    pub kind: u32,
+}
+
+pub struct MemoryMapIter {
+    thunk15: extern "C" fn(),
+    data: ThunkData,
+    first: bool,
+}
+
+impl MemoryMapIter {
+    pub fn new(thunk15: extern "C" fn()) -> Self {
+        Self {
+            thunk15,
+            data: ThunkData::new(),
+            first: true,
+        }
+    }
+}
+
+impl Iterator for MemoryMapIter {
+    type Item = OsMemoryEntry;
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.first {
+            self.first = false;
+        } else if self.data.ebx == 0 {
+            return None;
+        }
+
+        self.data.eax = 0xE820;
+        self.data.ecx = mem::size_of::<MemoryMapEntry>() as u32;
+        self.data.edx = 0x534D4150;
+        self.data.edi = MEMORY_MAP_ADDR as u32;
+
+        unsafe {
+            self.data.with(self.thunk15);
+        }
+
+        //TODO: return error?
+        assert_eq!({ self.data.eax }, 0x534D4150);
+        assert_eq!({ self.data.ecx }, mem::size_of::<MemoryMapEntry>() as u32);
+
+        let entry = unsafe { ptr::read(MEMORY_MAP_ADDR as *const MemoryMapEntry) };
+        Some(Self::Item {
+            base: entry.base,
+            size: entry.size,
+            kind: match entry.kind {
+                0 => OsMemoryKind::Null,
+                1 => OsMemoryKind::Free,
+                3 => OsMemoryKind::Reclaim,
+                _ => OsMemoryKind::Reserved,
+            },
+        })
+    }
+}
+
+pub unsafe fn memory_map(thunk15: extern "C" fn()) -> Option<(usize, usize)> {
+    let mut heap_limits = None;
+    for entry in MemoryMapIter::new(thunk15) {
+        let heap_start = 1024 * 1024;
+        if { entry.kind } == OsMemoryKind::Free
+            && entry.base <= heap_start as u64
+            && (entry.base + entry.size) >= heap_start as u64
+        {
+            let heap_end = cmp::min(entry.base + entry.size, usize::MAX as u64) as usize;
+            if heap_end >= heap_start {
+                heap_limits = Some((heap_start, heap_end - heap_start));
+            }
+        }
+
+        area_add(entry);
+    }
+    heap_limits
+}

src/os/bios/mod.rs

@@ -0,0 +1,318 @@
+use alloc::alloc::{Layout, alloc_zeroed};
+use core::{convert::TryFrom, mem, ptr, slice};
+use linked_list_allocator::LockedHeap;
+use spin::Mutex;
+
+use crate::KernelArgs;
+use crate::logger::LOGGER;
+use crate::os::{Os, OsHwDesc, OsKey, OsVideoMode};
+
+use self::disk::DiskBios;
+use self::memory_map::memory_map;
+use self::thunk::ThunkData;
+use self::vbe::VideoModeIter;
+use self::vga::{Vga, VgaTextColor};
+
+#[macro_use]
+mod macros;
+
+mod disk;
+mod memory_map;
+mod panic;
+pub(crate) mod serial;
+mod thunk;
+mod vbe;
+mod vga;
+
+// Real mode memory allocation, for use with thunk
+// 0x500 to 0x7BFF is free
+const DISK_BIOS_ADDR: usize = 0x70000; // 64 KiB at 448 KiB, ends at 512 KiB
+const VBE_CARD_INFO_ADDR: usize = 0x1000; // 512 bytes, ends at 0x11FF
+const VBE_MODE_INFO_ADDR: usize = 0x1200; // 256 bytes, ends at 0x12FF
+const VBE_EDID_ADDR: usize = 0x1300; // 128 bytes, ends at 0x137F
+const MEMORY_MAP_ADDR: usize = 0x1380; // 24 bytes, ends at 0x1397
+const DISK_ADDRESS_PACKET_ADDR: usize = 0x1398; // 16 bytes, ends at 0x13A7
+const THUNK_STACK_ADDR: usize = 0x7C00; // Grows downwards
+const VGA_ADDR: usize = 0xB8000;
+
+#[global_allocator]
+static ALLOCATOR: LockedHeap = LockedHeap::empty();
+
+pub(crate) static VGA: Mutex<Vga> = Mutex::new(unsafe { Vga::new(VGA_ADDR, 80, 25) });
+
+pub struct OsBios {
+    boot_disk: usize,
+    thunk10: extern "C" fn(),
+    thunk13: extern "C" fn(),
+    thunk15: extern "C" fn(),
+    thunk16: extern "C" fn(),
+}
+
+#[allow(dead_code)]
+#[derive(Copy, Clone, Debug)]
+#[repr(C, packed)]
+pub struct Rsdp {
+    signature: [u8; 8],
+    checksum: u8,
+    oemid: [u8; 6],
+    revision: u8,
+    rsdt_address: u32,
+}
+
+#[allow(dead_code)]
+#[derive(Copy, Clone, Debug)]
+#[repr(C, packed)]
+pub struct Xsdp {
+    rsdp: Rsdp,
+
+    length: u32,
+    xsdt_address: u64,
+    extended_checksum: u8,
+    reserved: [u8; 3],
+}
+
+unsafe fn search_rsdp(start: usize, end: usize) -> Option<(u64, u64)> {
+    unsafe {
+        // Align start up to 16 bytes
+        let mut addr = start.div_ceil(16) * 16;
+        // Search until reading the end of the Rsdp would be past the end of the memory area
+        while addr + mem::size_of::<Rsdp>() <= end {
+            let rsdp = ptr::read(addr as *const Rsdp);
+            if &rsdp.signature == b"RSD PTR " {
+                //TODO: check checksum?
+                if rsdp.revision == 0 {
+                    return Some((addr as u64, mem::size_of::<Rsdp>() as u64));
+                } else if rsdp.revision == 2 {
+                    let xsdp = ptr::read(addr as *const Xsdp);
+                    //TODO: check extended checksum?
+                    return Some((addr as u64, xsdp.length as u64));
+                }
+            }
+
+            // Rsdp is always aligned to 16 bytes
+            addr += 16;
+        }
+        None
+    }
+}
+
+impl Os for OsBios {
+    type D = DiskBios;
+    type V = VideoModeIter;
+
+    fn name(&self) -> &str {
+        "x86/BIOS"
+    }
+
+    fn alloc_zeroed_page_aligned(&self, size: usize) -> *mut u8 {
+        assert!(size != 0);
+
+        let page_size = self.page_size();
+        let pages = size.div_ceil(page_size);
+
+        let ptr =
+            unsafe { alloc_zeroed(Layout::from_size_align(pages * page_size, page_size).unwrap()) };
+
+        assert!(!ptr.is_null());
+        ptr
+    }
+
+    fn page_size(&self) -> usize {
+        4096
+    }
+
+    fn filesystem(
+        &self,
+        password_opt: Option<&[u8]>,
+    ) -> syscall::Result<redoxfs::FileSystem<DiskBios>> {
+        let disk = DiskBios::new(u8::try_from(self.boot_disk).unwrap(), self.thunk13);
+
+        //TODO: get block from partition table
+        let block = 2 * crate::MIBI as u64 / redoxfs::BLOCK_SIZE;
+        redoxfs::FileSystem::open(disk, password_opt, Some(block), false)
+    }
+
+    fn hwdesc(&self) -> OsHwDesc {
+        // See ACPI specification - Finding the RSDP on IA-PC Systems
+        unsafe {
+            let ebda_segment = ptr::read(0x40E as *const u16);
+            let ebda_addr = (ebda_segment as usize) << 4;
+            if let Some((addr, size)) =
+                search_rsdp(ebda_addr, ebda_addr + 1024).or(search_rsdp(0xE0000, 0xFFFFF))
+            {
+                // Copy to a page
+                let page_aligned = self.alloc_zeroed_page_aligned(size as usize);
+                ptr::copy(addr as *const u8, page_aligned, size as usize);
+                return OsHwDesc::Acpi(page_aligned as u64, size);
+            }
+        }
+        OsHwDesc::NotFound
+    }
+
+    fn video_outputs(&self) -> usize {
+        //TODO: return 1 only if vbe supported?
+        1
+    }
+
+    fn video_modes(&self, _output_i: usize) -> VideoModeIter {
+        VideoModeIter::new(self.thunk10)
+    }
+
+    fn set_video_mode(&self, _output_i: usize, mode: &mut OsVideoMode) {
+        // Set video mode
+        let mut data = ThunkData::new();
+        data.eax = 0x4F02;
+        data.ebx = mode.id;
+        unsafe {
+            data.with(self.thunk10);
+        }
+        //TODO: check result
+    }
+
+    fn best_resolution(&self, _output_i: usize) -> Option<(u32, u32)> {
+        let mut data = ThunkData::new();
+        data.eax = 0x4F15;
+        data.ebx = 0x01;
+        data.ecx = 0;
+        data.edx = 0;
+        data.edi = VBE_EDID_ADDR as u32;
+        unsafe {
+            data.with(self.thunk10);
+        }
+
+        if data.eax == 0x4F {
+            let edid = unsafe { slice::from_raw_parts(VBE_EDID_ADDR as *const u8, 128) };
+
+            Some((
+                (edid[0x38] as u32) | (((edid[0x3A] as u32) & 0xF0) << 4),
+                (edid[0x3B] as u32) | (((edid[0x3D] as u32) & 0xF0) << 4),
+            ))
+        } else {
+            log::warn!("Failed to get VBE EDID: 0x{:X}", { data.eax });
+            None
+        }
+    }
+
+    fn get_key(&self) -> OsKey {
+        // Read keypress
+        let mut data = ThunkData::new();
+        unsafe {
+            data.with(self.thunk16);
+        }
+        match (data.eax >> 8) as u8 {
+            0x4B => OsKey::Left,
+            0x4D => OsKey::Right,
+            0x48 => OsKey::Up,
+            0x50 => OsKey::Down,
+            0x0E => OsKey::Backspace,
+            0x53 => OsKey::Delete,
+            0x1C => OsKey::Enter,
+            _ => match data.eax as u8 {
+                0 => OsKey::Other,
+                b => OsKey::Char(b as char),
+            },
+        }
+    }
+
+    fn clear_text(&self) {
+        let mut vga = VGA.lock();
+        vga.clear();
+    }
+
+    fn get_text_position(&self) -> (usize, usize) {
+        let vga = VGA.lock();
+        (vga.x, vga.y)
+    }
+
+    fn set_text_position(&self, x: usize, y: usize) {
+        //TODO: ensure this is inside bounds!
+        let mut vga = VGA.lock();
+        vga.x = x;
+        vga.y = y;
+    }
+
+    fn set_text_highlight(&self, highlight: bool) {
+        let mut vga = VGA.lock();
+        if highlight {
+            vga.bg = VgaTextColor::Gray;
+            vga.fg = VgaTextColor::Black;
+        } else {
+            vga.bg = VgaTextColor::Black;
+            vga.fg = VgaTextColor::Gray;
+        }
+    }
+}
+
+#[unsafe(no_mangle)]
+pub unsafe extern "C" fn start(
+    kernel_entry: extern "C" fn(
+        page_table: usize,
+        stack: u64,
+        func: u64,
+        args: *const KernelArgs,
+        long_mode: usize,
+    ) -> !,
+    boot_disk: usize,
+    thunk10: extern "C" fn(),
+    thunk13: extern "C" fn(),
+    thunk15: extern "C" fn(),
+    thunk16: extern "C" fn(),
+) -> ! {
+    unsafe {
+        #[cfg(feature = "serial_debug")]
+        {
+            let mut com1 = serial::COM1.lock();
+            com1.init();
+            com1.write(b"SERIAL\n");
+        }
+
+        {
+            // Make sure we are in mode 3 (80x25 text mode)
+            let mut data = ThunkData::new();
+            data.eax = 0x03;
+            data.with(thunk10);
+        }
+
+        {
+            // Disable cursor
+            let mut data = ThunkData::new();
+            data.eax = 0x0100;
+            data.ecx = 0x3F00;
+            data.with(thunk10);
+        }
+
+        // Clear screen
+        VGA.lock().clear();
+
+        // Set logger
+        LOGGER.init();
+
+        let mut os = OsBios {
+            boot_disk,
+            thunk10,
+            thunk13,
+            thunk15,
+            thunk16,
+        };
+
+        let (heap_start, heap_size) = memory_map(os.thunk15).expect("No memory for heap");
+
+        ALLOCATOR.lock().init(heap_start as *mut u8, heap_size);
+
+        let (page_phys, func, args) = crate::main(&mut os);
+
+        kernel_entry(
+            page_phys,
+            args.stack_base
+                + args.stack_size
+                + if crate::KERNEL_64BIT {
+                    crate::arch::x64::PHYS_OFFSET
+                } else {
+                    crate::arch::x32::PHYS_OFFSET as u64
+                },
+            func,
+            &args,
+            if crate::KERNEL_64BIT { 1 } else { 0 },
+        );
+    }
+}

src/os/bios/panic.rs

@@ -0,0 +1,16 @@
+//! Intrinsics for panic handling
+
+use core::alloc::Layout;
+use core::arch::asm;
+use core::panic::PanicInfo;
+
+/// Required to handle panics
+#[panic_handler]
+pub fn rust_begin_unwind(info: &PanicInfo) -> ! {
+    unsafe {
+        println!("BOOTLOADER PANIC:\n{}", info);
+        loop {
+            asm!("hlt");
+        }
+    }
+}

src/os/bios/serial.rs

@@ -0,0 +1,9 @@
+use spin::Mutex;
+use syscall::Pio;
+
+use crate::serial_16550::SerialPort;
+
+pub static COM1: Mutex<SerialPort<Pio<u8>>> = Mutex::new(SerialPort::<Pio<u8>>::new(0x3F8));
+pub static COM2: Mutex<SerialPort<Pio<u8>>> = Mutex::new(SerialPort::<Pio<u8>>::new(0x2F8));
+pub static COM3: Mutex<SerialPort<Pio<u8>>> = Mutex::new(SerialPort::<Pio<u8>>::new(0x3E8));
+pub static COM4: Mutex<SerialPort<Pio<u8>>> = Mutex::new(SerialPort::<Pio<u8>>::new(0x2E8));

src/os/bios/thunk.rs

@@ -0,0 +1,52 @@
+use core::ptr;
+
+use super::THUNK_STACK_ADDR;
+
+#[allow(dead_code)]
+#[derive(Clone, Copy, Debug)]
+#[repr(C, packed)]
+pub struct ThunkData {
+    pub es: u16,
+    pub edi: u32,
+    pub esi: u32,
+    pub ebp: u32,
+    pub ebx: u32,
+    pub edx: u32,
+    pub ecx: u32,
+    pub eax: u32,
+}
+
+impl ThunkData {
+    pub fn new() -> Self {
+        Self {
+            es: 0,
+            edi: 0,
+            esi: 0,
+            ebp: 0,
+            ebx: 0,
+            edx: 0,
+            ecx: 0,
+            eax: 0,
+        }
+    }
+
+    pub unsafe fn save(&self) {
+        unsafe {
+            ptr::write((THUNK_STACK_ADDR - 64) as *mut ThunkData, *self);
+        }
+    }
+
+    pub unsafe fn load(&mut self) {
+        unsafe {
+            *self = ptr::read((THUNK_STACK_ADDR - 64) as *const ThunkData);
+        }
+    }
+
+    pub unsafe fn with(&mut self, f: extern "C" fn()) {
+        unsafe {
+            self.save();
+            f();
+            self.load();
+        }
+    }
+}

src/os/bios/vbe.rs

@@ -0,0 +1,151 @@
+use core::ptr;
+use log::error;
+
+use crate::os::OsVideoMode;
+
+use super::{ThunkData, VBE_CARD_INFO_ADDR, VBE_MODE_INFO_ADDR};
+
+#[derive(Clone, Copy, Debug)]
+#[repr(C, packed)]
+pub struct VbeFarPtr {
+    pub offset: u16,
+    pub segment: u16,
+}
+
+impl VbeFarPtr {
+    pub unsafe fn as_ptr<T>(&self) -> *const T {
+        (((self.segment as usize) << 4) + (self.offset as usize)) as *const T
+    }
+}
+
+#[derive(Clone, Copy, Debug)]
+#[repr(C, packed)]
+pub struct VbeCardInfo {
+    pub signature: [u8; 4],
+    pub version: u16,
+    pub oemstring: VbeFarPtr,
+    pub capabilities: [u8; 4],
+    pub videomodeptr: VbeFarPtr,
+    pub totalmemory: u16,
+    pub oemsoftwarerev: u16,
+    pub oemvendornameptr: VbeFarPtr,
+    pub oemproductnameptr: VbeFarPtr,
+    pub oemproductrevptr: VbeFarPtr,
+    pub reserved: [u8; 222],
+    pub oemdata: [u8; 256],
+}
+
+#[derive(Clone, Copy, Debug)]
+#[repr(C, packed)]
+pub struct VbeModeInfo {
+    pub attributes: u16,
+    pub win_a: u8,
+    pub win_b: u8,
+    pub granularity: u16,
+    pub winsize: u16,
+    pub segment_a: u16,
+    pub segment_b: u16,
+    pub winfuncptr: u32,
+    pub bytesperscanline: u16,
+    pub xresolution: u16,
+    pub yresolution: u16,
+    pub xcharsize: u8,
+    pub ycharsize: u8,
+    pub numberofplanes: u8,
+    pub bitsperpixel: u8,
+    pub numberofbanks: u8,
+    pub memorymodel: u8,
+    pub banksize: u8,
+    pub numberofimagepages: u8,
+    pub unused: u8,
+    pub redmasksize: u8,
+    pub redfieldposition: u8,
+    pub greenmasksize: u8,
+    pub greenfieldposition: u8,
+    pub bluemasksize: u8,
+    pub bluefieldposition: u8,
+    pub rsvdmasksize: u8,
+    pub rsvdfieldposition: u8,
+    pub directcolormodeinfo: u8,
+    pub physbaseptr: u32,
+    pub offscreenmemoryoffset: u32,
+    pub offscreenmemsize: u16,
+    pub reserved: [u8; 206],
+}
+
+pub struct VideoModeIter {
+    thunk10: extern "C" fn(),
+    mode_ptr: *const u16,
+}
+
+impl VideoModeIter {
+    pub fn new(thunk10: extern "C" fn()) -> Self {
+        // Get card info
+        let mut data = ThunkData::new();
+        data.eax = 0x4F00;
+        data.edi = VBE_CARD_INFO_ADDR as u32;
+        unsafe {
+            data.with(thunk10);
+        }
+        let mode_ptr = if data.eax == 0x004F {
+            let card_info = unsafe { ptr::read(VBE_CARD_INFO_ADDR as *const VbeCardInfo) };
+            unsafe { card_info.videomodeptr.as_ptr::<u16>() }
+        } else {
+            error!("Failed to read VBE card info: 0x{:04X}", { data.eax });
+            ptr::null()
+        };
+        Self { thunk10, mode_ptr }
+    }
+}
+
+impl Iterator for VideoModeIter {
+    type Item = OsVideoMode;
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.mode_ptr.is_null() {
+            return None;
+        }
+
+        loop {
+            // Set bit 14 to get linear frame buffer
+            let mode = unsafe { *self.mode_ptr } | (1 << 14);
+            if mode == 0xFFFF {
+                return None;
+            }
+            self.mode_ptr = unsafe { self.mode_ptr.add(1) };
+
+            // Get mode info
+            let mut data = ThunkData::new();
+            data.eax = 0x4F01;
+            data.ecx = mode as u32;
+            data.edi = VBE_MODE_INFO_ADDR as u32;
+            unsafe {
+                data.with(self.thunk10);
+            }
+            if data.eax == 0x004F {
+                let mode_info = unsafe { ptr::read(VBE_MODE_INFO_ADDR as *const VbeModeInfo) };
+
+                // We only support 32-bits per pixel modes
+                if mode_info.bitsperpixel != 32 {
+                    continue;
+                }
+
+                let width = mode_info.xresolution as u32;
+                let height = mode_info.yresolution as u32;
+                //TODO: support stride that is not a multiple of 4
+                let stride = mode_info.bytesperscanline as u32 / 4;
+
+                return Some(OsVideoMode {
+                    id: mode as u32,
+                    width,
+                    height,
+                    stride,
+                    base: mode_info.physbaseptr as u64,
+                });
+            } else {
+                error!("Failed to read VBE mode 0x{:04X} info: 0x{:04X}", mode, {
+                    data.eax
+                });
+            }
+        }
+    }
+}

src/os/bios/vga.rs

@@ -0,0 +1,121 @@
+use core::{fmt, slice};
+
+#[derive(Clone, Copy)]
+#[repr(C, packed)]
+pub struct VgaTextBlock {
+    pub char: u8,
+    pub color: u8,
+}
+
+#[allow(dead_code)]
+#[derive(Clone, Copy)]
+#[repr(u8)]
+pub enum VgaTextColor {
+    Black = 0,
+    Blue = 1,
+    Green = 2,
+    Cyan = 3,
+    Red = 4,
+    Purple = 5,
+    Brown = 6,
+    Gray = 7,
+    DarkGray = 8,
+    LightBlue = 9,
+    LightGreen = 10,
+    LightCyan = 11,
+    LightRed = 12,
+    LightPurple = 13,
+    Yellow = 14,
+    White = 15,
+}
+
+pub struct Vga {
+    pub base: usize,
+    pub width: usize,
+    pub height: usize,
+    pub x: usize,
+    pub y: usize,
+    pub bg: VgaTextColor,
+    pub fg: VgaTextColor,
+}
+
+impl Vga {
+    pub const unsafe fn new(base: usize, width: usize, height: usize) -> Self {
+        Self {
+            base,
+            width,
+            height,
+            x: 0,
+            y: 0,
+            bg: VgaTextColor::Black,
+            fg: VgaTextColor::Gray,
+        }
+    }
+
+    pub unsafe fn blocks(&mut self) -> &'static mut [VgaTextBlock] {
+        unsafe {
+            slice::from_raw_parts_mut(self.base as *mut VgaTextBlock, self.width * self.height)
+        }
+    }
+
+    pub fn clear(&mut self) {
+        self.x = 0;
+        self.y = 0;
+        let blocks = unsafe { self.blocks() };
+        for i in 0..blocks.len() {
+            blocks[i] = VgaTextBlock {
+                char: 0,
+                color: ((self.bg as u8) << 4) | (self.fg as u8),
+            };
+        }
+    }
+}
+
+impl fmt::Write for Vga {
+    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+        let blocks = unsafe { self.blocks() };
+        for c in s.chars() {
+            if self.x >= self.width {
+                self.x = 0;
+                self.y += 1;
+            }
+            while self.y >= self.height {
+                for y in 1..self.height {
+                    for x in 0..self.width {
+                        let i = y * self.width + x;
+                        let j = i - self.width;
+                        blocks[j] = blocks[i];
+                        if y + 1 == self.height {
+                            blocks[i].char = 0;
+                        }
+                    }
+                }
+                self.y -= 1;
+            }
+            match c {
+                '\x08' => {
+                    if self.x > 0 {
+                        self.x -= 1;
+                    }
+                }
+                '\r' => {
+                    self.x = 0;
+                }
+                '\n' => {
+                    self.x = 0;
+                    self.y += 1;
+                }
+                _ => {
+                    let i = self.y * self.width + self.x;
+                    if let Some(block) = blocks.get_mut(i) {
+                        block.char = c as u8;
+                        block.color = ((self.bg as u8) << 4) | (self.fg as u8);
+                    }
+                    self.x += 1;
+                }
+            }
+        }
+
+        Ok(())
+    }
+}

src/os/mod.rs

@@ -0,0 +1,95 @@
+use redoxfs::Disk;
+
+#[cfg(all(target_arch = "x86", target_os = "none"))]
+pub use self::bios::*;
+
+#[cfg(all(target_arch = "x86", target_os = "none"))]
+#[macro_use]
+mod bios;
+
+#[cfg(any(target_arch = "riscv64", target_os = "uefi"))]
+#[allow(unused_imports)]
+pub use self::uefi::*;
+
+#[cfg(any(target_arch = "riscv64", target_os = "uefi"))]
+#[macro_use]
+mod uefi;
+
+#[derive(Clone, Copy, Debug)]
+pub enum OsHwDesc {
+    Acpi(u64, u64),
+    DeviceTree(u64, u64),
+    NotFound,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub enum OsKey {
+    Left,
+    Right,
+    Up,
+    Down,
+    Backspace,
+    Delete,
+    Enter,
+    Char(char),
+    Other,
+}
+
+// Keep synced with BootloaderMemoryKind in kernel
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+#[repr(u64)]
+pub enum OsMemoryKind {
+    Null = 0,
+    Free = 1,
+    Reclaim = 2,
+    Reserved = 3,
+}
+
+// Keep synced with BootloaderMemoryEntry in kernel
+#[derive(Clone, Copy, Debug)]
+#[repr(C, packed(8))]
+pub struct OsMemoryEntry {
+    pub base: u64,
+    pub size: u64,
+    pub kind: OsMemoryKind,
+}
+
+#[derive(Clone, Copy, Debug)]
+pub struct OsVideoMode {
+    pub id: u32,
+    pub width: u32,
+    pub height: u32,
+    pub stride: u32,
+    pub base: u64,
+}
+
+pub trait Os {
+    type D: Disk;
+    type V: Iterator<Item = OsVideoMode>;
+
+    fn name(&self) -> &str;
+
+    fn alloc_zeroed_page_aligned(&self, size: usize) -> *mut u8;
+
+    #[allow(dead_code)]
+    fn page_size(&self) -> usize;
+
+    fn filesystem(
+        &self,
+        password_opt: Option<&[u8]>,
+    ) -> syscall::Result<redoxfs::FileSystem<Self::D>>;
+
+    fn hwdesc(&self) -> OsHwDesc;
+
+    fn video_outputs(&self) -> usize;
+    fn video_modes(&self, output_i: usize) -> Self::V;
+    fn set_video_mode(&self, output_i: usize, mode: &mut OsVideoMode);
+    fn best_resolution(&self, output_i: usize) -> Option<(u32, u32)>;
+
+    fn get_key(&self) -> OsKey;
+
+    fn clear_text(&self);
+    fn get_text_position(&self) -> (usize, usize);
+    fn set_text_position(&self, x: usize, y: usize);
+    fn set_text_highlight(&self, highlight: bool);
+}

src/os/uefi/acpi.rs

@@ -0,0 +1,110 @@
+use core::slice;
+use uefi::guid::{ACPI_20_TABLE_GUID, ACPI_TABLE_GUID};
+
+use crate::Os;
+
+struct Invalid;
+
+fn validate_rsdp(address: usize, _v2: bool) -> core::result::Result<usize, Invalid> {
+    #[repr(C, packed)]
+    #[derive(Clone, Copy, Debug)]
+    struct Rsdp {
+        signature: [u8; 8], // b"RSD PTR "
+        chksum: u8,
+        oem_id: [u8; 6],
+        revision: u8,
+        rsdt_addr: u32,
+        // the following fields are only available for ACPI 2.0, and are reserved otherwise
+        length: u32,
+        xsdt_addr: u64,
+        extended_chksum: u8,
+        _rsvd: [u8; 3],
+    }
+    // paging is not enabled at this stage; we can just read the physical address here.
+    let rsdp_bytes =
+        unsafe { core::slice::from_raw_parts(address as *const u8, core::mem::size_of::<Rsdp>()) };
+    let rsdp = unsafe {
+        (rsdp_bytes.as_ptr() as *const Rsdp)
+            .as_ref::<'static>()
+            .unwrap()
+    };
+
+    log::debug!("RSDP: {:?}", rsdp);
+
+    if rsdp.signature != *b"RSD PTR " {
+        return Err(Invalid);
+    }
+    let mut base_sum = 0u8;
+    for base_byte in &rsdp_bytes[..20] {
+        base_sum = base_sum.wrapping_add(*base_byte);
+    }
+    if base_sum != 0 {
+        return Err(Invalid);
+    }
+
+    if rsdp.revision == 2 {
+        let mut extended_sum = 0u8;
+        for byte in rsdp_bytes {
+            extended_sum = extended_sum.wrapping_add(*byte);
+        }
+
+        if extended_sum != 0 {
+            return Err(Invalid);
+        }
+    }
+
+    let length = if rsdp.revision == 2 {
+        rsdp.length as usize
+    } else {
+        core::mem::size_of::<Rsdp>()
+    };
+
+    Ok(length)
+}
+
+pub(crate) fn find_acpi_table_pointers(os: &impl Os) -> Option<(u64, u64)> {
+    let cfg_tables = std::system_table().config_tables();
+    let mut acpi = None;
+    let mut acpi2 = None;
+    for cfg_table in cfg_tables.iter() {
+        if cfg_table.VendorGuid == ACPI_TABLE_GUID {
+            match validate_rsdp(cfg_table.VendorTable, false) {
+                Ok(length) => {
+                    acpi = Some(unsafe {
+                        core::slice::from_raw_parts(cfg_table.VendorTable as *const u8, length)
+                    });
+                }
+                Err(_) => log::warn!(
+                    "Found RSDP that was not valid at {:p}",
+                    cfg_table.VendorTable as *const u8
+                ),
+            }
+        } else if cfg_table.VendorGuid == ACPI_20_TABLE_GUID {
+            match validate_rsdp(cfg_table.VendorTable, true) {
+                Ok(length) => {
+                    acpi2 = Some(unsafe {
+                        core::slice::from_raw_parts(cfg_table.VendorTable as *const u8, length)
+                    });
+                }
+                Err(_) => log::warn!(
+                    "Found RSDP that was not valid at {:p}",
+                    cfg_table.VendorTable as *const u8
+                ),
+            }
+        }
+    }
+
+    let rsdp_area = acpi2.or(acpi).unwrap_or(&[]);
+
+    if !rsdp_area.is_empty() {
+        unsafe {
+            // Copy to page aligned area
+            let size = rsdp_area.len();
+            let base = os.alloc_zeroed_page_aligned(size);
+            slice::from_raw_parts_mut(base, size).copy_from_slice(rsdp_area);
+            Some((base as u64, size as u64))
+        }
+    } else {
+        None
+    }
+}

src/os/uefi/arch/aarch64.rs

@@ -0,0 +1,236 @@
+use core::{arch::asm, fmt::Write, mem, slice};
+use uefi::status::Result;
+
+use crate::{
+    KernelArgs,
+    arch::{ENTRY_ADDRESS_MASK, PAGE_ENTRIES, PF_PRESENT, PF_TABLE, PHYS_OFFSET},
+    logger::LOGGER,
+};
+
+use super::super::{OsEfi, memory_map::memory_map};
+
+unsafe fn dump_page_tables(table_phys: u64, table_virt: u64, table_level: u64) {
+    unsafe {
+        let entries = slice::from_raw_parts(table_phys as *const u64, PAGE_ENTRIES);
+        for (i, entry) in entries.iter().enumerate() {
+            let phys = entry & ENTRY_ADDRESS_MASK;
+            let flags = entry & !ENTRY_ADDRESS_MASK;
+            if flags & PF_PRESENT == 0 {
+                continue;
+            }
+            let mut shift = 39u64;
+            for _ in 0..table_level {
+                shift -= 9;
+                print!("\t");
+            }
+            let virt = table_virt + (i as u64) << shift;
+            println!(
+                "index {} virt {:#x}: phys {:#x} flags {:#x}",
+                i, virt, phys, flags
+            );
+            if table_level < 3 && flags & PF_TABLE == PF_TABLE {
+                dump_page_tables(phys, virt, table_level + 1);
+            }
+        }
+    }
+}
+
+unsafe extern "C" fn kernel_entry(
+    page_phys: usize,
+    stack: u64,
+    func: u64,
+    args: *const KernelArgs,
+) -> ! {
+    unsafe {
+        // Read memory map and exit boot services
+        memory_map().exit_boot_services();
+
+        let currentel: u64;
+        asm!(
+            "mrs {0}, currentel", // Read current exception level
+            out(reg) currentel,
+        );
+        if currentel == (2 << 2) {
+            // Need to drop from EL2 to EL1
+
+            // Allow access to timers
+            asm!(
+                "mrs {0}, cnthctl_el2",
+                "orr {0}, {0}, #0x3",
+                "msr cnthctl_el2, {0}",
+                "msr cntvoff_el2, xzr",
+                out(reg) _
+            );
+
+            // Initialize ID registers
+            asm!(
+                "mrs {0}, midr_el1",
+                "msr vpidr_el2, {0}",
+                "mrs {0}, mpidr_el1",
+                "msr vmpidr_el2, {0}",
+                out(reg) _
+            );
+
+            // Disable traps
+            asm!(
+                "msr cptr_el2, {0}",
+                "msr hstr_el2, xzr",
+                in(reg) 0x33FF as u64
+            );
+
+            // Enable floating point
+            asm!(
+                "msr cpacr_el1, {0}",
+                in(reg) (3 << 20) as u64
+            );
+
+            // Set EL1 system control register
+            asm!(
+                "msr sctlr_el1, {0}",
+                in(reg) 0x30d00800 as u64
+            );
+
+            // Set EL1 stack and VBAR
+            asm!(
+                "mov {0}, sp",
+                "msr sp_el1, {0}",
+                "mrs {0}, vbar_el2",
+                "msr vbar_el1, {0}",
+                out(reg) _
+            );
+
+            // Configure execution state of EL1 as aarch64 and disable hypervisor call.
+            asm!(
+                "msr hcr_el2, {0}",
+                in(reg) ((1u64 << 31) | (1u64 << 29)),
+            );
+
+            // Set saved program status register
+            asm!(
+                "msr spsr_el2, {0}",
+                in(reg) 0x3C5 as u64
+            );
+
+            // Switch to EL1
+            asm!(
+                "adr {0}, 1f",
+                "msr elr_el2, {0}",
+                "eret",
+                "1:",
+                out(reg) _
+            );
+        } else if currentel == (1 << 2) {
+            // Already in EL1
+        } else {
+            //TODO: what to do if not EL2 or already EL1?
+            loop {
+                asm!("wfi");
+            }
+        }
+
+        // Disable MMU
+        asm!(
+            "mrs {0}, sctlr_el1", // Read system control register
+            "bic {0}, {0}, 1", // Clear MMU enable bit
+            "msr sctlr_el1, {0}", // Write system control register
+            "isb", // Instruction sync barrier
+            out(reg) _,
+        );
+
+        // Set MAIR
+        // You can think about MAIRs as of an array with 8 elements each of 8 bits long.
+        // You can store inside MAIRs up to 8 attributes sets and reffer them by the index 0..7 stored in INDX (AttrIndx) field of the table descriptor.
+        // https://lowenware.com/blog/aarch64-mmu-programming/
+        // https://developer.arm.com/documentation/102376/0200/Describing-memory-in-AArch64
+        // https://developer.arm.com/documentation/ddi0595/2021-06/AArch64-Registers/MAIR-EL1--Memory-Attribute-Indirection-Register--EL1-
+        // Attribute 0 (0xFF) - normal memory, caches are enabled
+        // Attribute 1 (0x44) - normal memory, caches are disabled. Atomics wouldn't work here if memory doesn't support exclusive access (most real hardware don't)
+        // Attribute 2 (0x00) - nGnRnE device memory, caches are disabled, gathering, re-ordering, and early write acknowledgement aren't allowed.
+        asm!(
+            "msr mair_el1, {0}",
+            in(reg) 0x00000000000044FF as u64, // MAIR: Arrange for Device, Normal Non-Cache, Normal Write-Back access types
+        );
+
+        // Set TCR
+        asm!(
+            "mrs {1}, id_aa64mmfr0_el1", // Read memory model feature register
+            "bfi {0}, {1}, #32, #3",
+            "msr tcr_el1, {0}", // Write translation control register
+            "isb", // Instruction sync barrier
+            in(reg) 0x1085100510u64, // TCR: (TxSZ, ASID_16, TG1_4K, Cache Attrs, SMP Attrs)
+            out(reg) _,
+        );
+
+        // Set page tables
+        asm!(
+            "dsb sy", // Data sync barrier
+            "msr ttbr1_el1, {0}", // Set higher half page table
+            "msr ttbr0_el1, {0}", // Set lower half page table
+            "isb", // Instruction sync barrier
+            "dsb ishst", // Data sync barrier, only for stores, and only for inner shareable domain
+            "tlbi vmalle1is", // Invalidate TLB
+            "dsb ish", // Dta sync bariar, only for inner shareable domain
+            "isb", // Instruction sync barrier
+            in(reg) page_phys,
+        );
+
+        // Enable MMU
+        asm!(
+            "mrs {2}, sctlr_el1", // Read system control register
+            "bic {2}, {2}, {0}", // Clear bits
+            "orr {2}, {2}, {1}", // Set bits
+            "msr sctlr_el1, {2}", // Write system control register
+            "isb", // Instruction sync barrier
+            in(reg) 0x32802c2u64,  // Clear SCTLR bits: (EE, EOE, IESB, WXN, UMA, ITD, THEE, A)
+            in(reg) 0x3485d13du64, // Set SCTLR bits: (LSMAOE, nTLSMD, UCI, SPAN, nTWW, nTWI, UCT, DZE, I, SED, SA0, SA, C, M, CP15BEN)
+            out(reg) _,
+        );
+
+        // Set stack
+        asm!("mov sp, {}", in(reg) stack);
+
+        // Call kernel entry
+        let entry_fn: extern "C" fn(*const KernelArgs) -> ! = mem::transmute(func);
+        entry_fn(args);
+    }
+}
+
+pub fn main() -> Result<()> {
+    LOGGER.init();
+
+    let mut os = OsEfi::new();
+
+    // Disable cursor
+    let _ = (os.st.ConsoleOut.EnableCursor)(os.st.ConsoleOut, false);
+
+    let currentel: u64;
+    unsafe {
+        asm!(
+            "mrs {0}, currentel", // Read current exception level
+            out(reg) currentel,
+        );
+    }
+    log::info!("Currently in EL{}", (currentel >> 2) & 3);
+
+    let (page_phys, func, args) = crate::main(&mut os);
+
+    unsafe {
+        let stack = args.stack_base + args.stack_size + PHYS_OFFSET;
+
+        // dump_page_tables(page_phys as _, 0, 0);
+
+        println!(
+            "kernel_entry({:#x}, {:#x}, {:#x}, {:p})",
+            page_phys, stack, func, &args
+        );
+        println!("{:#x?}", args);
+
+        kernel_entry(page_phys, stack, func, &args);
+    }
+}
+
+pub fn disable_interrupts() {
+    unsafe {
+        asm!("msr daifset, #2");
+    }
+}

src/os/uefi/arch/mod.rs

@@ -0,0 +1,14 @@
+#[cfg(target_arch = "aarch64")]
+mod aarch64;
+#[cfg(target_arch = "aarch64")]
+pub use self::aarch64::*;
+
+#[cfg(target_arch = "x86_64")]
+mod x86_64;
+#[cfg(target_arch = "x86_64")]
+pub use self::x86_64::*;
+
+#[cfg(target_arch = "riscv64")]
+mod riscv64;
+#[cfg(target_arch = "riscv64")]
+pub use self::riscv64::*;

src/os/uefi/arch/riscv64/boot_protocol.rs

@@ -0,0 +1,45 @@
+use std::proto::Protocol;
+use uefi::guid::Guid;
+use uefi::status::{Result, Status};
+
+#[derive(Debug)]
+#[repr(C)]
+struct RiscVEfiBootProtocol {
+    pub revision: u64,
+    pub efi_get_boot_hartid:
+        unsafe extern "efiapi" fn(this: *mut Self, phartid: *mut usize) -> Status,
+}
+
+impl RiscVEfiBootProtocol {
+    pub const GUID: Guid = Guid::parse_str("ccd15fec-6f73-4eec-8395-3e69e4b940bf");
+    // pub const REVISION: u64 = 0x00010000;
+}
+
+struct RiscVEfiBoot(pub &'static mut RiscVEfiBootProtocol);
+
+impl Protocol<RiscVEfiBootProtocol> for RiscVEfiBoot {
+    fn guid() -> Guid {
+        RiscVEfiBootProtocol::GUID
+    }
+
+    fn new(inner: &'static mut RiscVEfiBootProtocol) -> Self {
+        Self(inner)
+    }
+}
+
+impl RiscVEfiBoot {
+    pub fn efi_get_boot_hartid(&mut self) -> Result<usize> {
+        let mut boot_hartid: usize = 0;
+        match unsafe { (self.0.efi_get_boot_hartid)(self.0, &mut boot_hartid) } {
+            ok if ok.is_success() => Ok(boot_hartid),
+            err => Err(err),
+        }
+    }
+}
+
+pub fn efi_get_boot_hartid() -> Result<usize> {
+    let handles = RiscVEfiBoot::locate_handle()?;
+    let handle = handles.first().ok_or(Status::NOT_FOUND)?;
+    let mut proto = RiscVEfiBoot::handle_protocol(*handle)?;
+    proto.efi_get_boot_hartid()
+}

src/os/uefi/arch/riscv64/coff_helper.rs

@@ -0,0 +1,113 @@
+use core::arch::{global_asm, naked_asm};
+
+/// Unfortunately this can't be written in Rust because it might use some not-yet
+/// relocated data such as jump tables
+#[unsafe(naked)]
+#[unsafe(no_mangle)]
+extern "C" fn coff_relocate(dynentry: *const u8, base: usize) -> usize {
+    unsafe {
+        naked_asm!(
+            "
+    mv   t4, zero // RELA
+    li   t5, -1   // RELASZ
+    li   t6, -1   // RELAENT
+
+5:
+    ld   t0, 0(a0)
+    beqz t0, 6f
+    addi a0, a0, 16
+    addi t0, t0, -4
+    bltz t0, 3f     // fail on DT_NEEDED=1, DT_PLTRELSZ=2,  DT_PLTGOT=3
+    addi t0, t0, -3
+    bltz t0, 5b     // skip DT_HASH=4, DT_STRTAB=5, DT_SYMTAB=6
+    bnez t0, 2f
+    ld   t4, -8(a0) // DT_RELA=7
+    j    5b
+2:  addi t0, t0, -1 // DT_RELASZ=8
+    bnez t0, 2f
+    ld   t5, -8(a0)
+    j    5b
+2:  addi t0, t0, -1 // DT_RELAENT=9
+    bnez t0, 2f
+    ld   t6, -8(a0)
+    j    5b
+2:  addi t0, t0, -3
+    bltz t0, 5b     // skip  DT_STRSZ=10, DT_SYMENT=11
+    addi t0, t0, -2
+    bltz t0, 3f     // fail on DT_INIT=12, DT_FINI=13
+    beqz t0, 5b     // skip DT_SONAME=14
+2:  addi t0, t0, -2
+    bltz t0, 3f     // fail on DT_RPATH
+    beqz t0, 5b     // skip SYMBOLIC=16
+    li   t1, 0x6ffffef5-16
+    sub  t0, t0, t1
+    beqz t0, 5b     // skip DT_GNU_HASH=0x6ffffef5
+    nop
+3:  // error
+    mv   a0, zero
+    ret
+
+6:
+    bnez t4, 2f
+4: // success
+    li   a0, 1
+    ret
+2:  bltz t5, 3b
+    blez t6, 3b
+
+    add  t4, t4, a1
+    add  t5, t5, t4
+7:
+    bge  t4, t5, 4b
+    ld   t0, 0(t4)   // r_offset
+    add  t0, t0, a1
+    lwu  t1, 8(t4)   // r_type
+    ld   t2, 16(t4)  // r_addend
+    add  t4, t4, t6
+    addi t1, t1, -3  // R_RISCV_RELATIVE=3
+    bnez t1, 3b
+    add  t2, t2, a1  // RELATIVE: *value = base + addend
+    sd   t2, 0(t0)
+    j    7b
+    "
+        )
+    }
+}
+
+global_asm!(
+    r#"
+   .global coff_start
+coff_start:
+    .option norelax
+    addi sp, sp, -24
+    sd   a0, 0(sp)
+    sd   a1, 8(sp)
+    sd   ra, 16(sp)
+    lla  a0, _DYNAMIC
+    lla  a1, ImageBase  // actual loaded image base to relocate to
+    jal  coff_relocate
+    .option relax
+    mv   t0, a0
+    ld   a0, 0(sp)
+    ld   a1, 8(sp)
+    ld   ra, 16(sp)
+    addi sp, sp, 24
+    beqz t0, 2f
+    j    efi_main
+2:  ret
+"#
+);
+
+// GNU-EFI .reloc trick to make objcopy say we are relocatable
+global_asm!(
+    r#"
+    .section .data
+    DUMMY_RELOCATION: .4byte 0
+    .section .reloc, "a"
+
+2:
+    .4byte DUMMY_RELOCATION - ImageBase
+    .4byte 12
+    .4byte 0
+"#
+);

src/os/uefi/arch/riscv64/mod.rs

@@ -0,0 +1,70 @@
+use crate::KernelArgs;
+use crate::arch::PHYS_OFFSET;
+use crate::arch::SATP_BITS;
+use crate::logger::LOGGER;
+use crate::os::OsEfi;
+use crate::os::uefi::memory_map::memory_map;
+use core::arch::asm;
+use core::mem;
+use uefi::status::Result;
+
+mod boot_protocol;
+mod coff_helper;
+
+pub use boot_protocol::*;
+
+unsafe extern "C" fn kernel_entry(
+    page_phys: usize,
+    stack: u64,
+    func: u64,
+    args: *const KernelArgs,
+) -> ! {
+    unsafe {
+        // Set page tables
+        asm!(
+        "csrw satp, {0}",
+        "sfence.vma",
+        in(reg) (page_phys >> 12 | SATP_BITS << 60)
+        );
+
+        let entry_fn: extern "C" fn(*const KernelArgs) -> ! = mem::transmute(func);
+
+        // Set stack and go to kernel
+        asm!("mv sp, {0}",
+        "mv a0, {1}",
+        "jalr {2}",
+        in(reg) stack,
+        in(reg) args,
+        in(reg) entry_fn
+        );
+        loop {}
+    }
+}
+
+pub fn main() -> Result<()> {
+    LOGGER.init();
+
+    let mut os = OsEfi::new();
+
+    // Disable cursor
+    let _ = (os.st.ConsoleOut.EnableCursor)(os.st.ConsoleOut, false);
+
+    let (page_phys, func, args) = crate::main(&mut os);
+
+    unsafe {
+        memory_map().exit_boot_services();
+
+        kernel_entry(
+            page_phys,
+            args.stack_base + args.stack_size + PHYS_OFFSET,
+            func,
+            &args,
+        );
+    }
+}
+
+pub fn disable_interrupts() {
+    unsafe {
+        asm!("csrci sstatus, 2");
+    }
+}

src/os/uefi/arch/x86_64.rs

@@ -0,0 +1,82 @@
+use core::{arch::asm, mem};
+use uefi::status::Result;
+use x86::{
+    controlregs::{self, Cr0, Cr4},
+    msr,
+};
+
+use crate::{KernelArgs, logger::LOGGER};
+
+use super::super::{OsEfi, memory_map::memory_map};
+
+unsafe extern "C" fn kernel_entry(
+    page_phys: usize,
+    stack: u64,
+    func: u64,
+    args: *const KernelArgs,
+) -> ! {
+    unsafe {
+        // Read memory map and exit boot services
+        memory_map().exit_boot_services();
+
+        // Enable FXSAVE/FXRSTOR, Page Global, Page Address Extension, and Page Size Extension
+        let mut cr4 = controlregs::cr4();
+        cr4 |= Cr4::CR4_ENABLE_SSE
+            | Cr4::CR4_ENABLE_GLOBAL_PAGES
+            | Cr4::CR4_ENABLE_PAE
+            | Cr4::CR4_ENABLE_PSE;
+        controlregs::cr4_write(cr4);
+
+        // Enable Long mode and NX bit
+        let mut efer = msr::rdmsr(msr::IA32_EFER);
+        efer |= 1 << 11 | 1 << 8;
+        msr::wrmsr(msr::IA32_EFER, efer);
+
+        // Set new page map
+        controlregs::cr3_write(page_phys as u64);
+
+        // Enable paging, write protect kernel, protected mode
+        let mut cr0 = controlregs::cr0();
+        cr0 |= Cr0::CR0_ENABLE_PAGING | Cr0::CR0_WRITE_PROTECT | Cr0::CR0_PROTECTED_MODE;
+        controlregs::cr0_write(cr0);
+
+        // Set stack
+        asm!("mov rsp, {}", in(reg) stack);
+
+        // Call kernel entry
+        let entry_fn: extern "sysv64" fn(*const KernelArgs) -> ! = mem::transmute(func);
+        entry_fn(args);
+    }
+}
+
+pub fn main() -> Result<()> {
+    LOGGER.init();
+
+    let mut os = OsEfi::new();
+
+    // Disable cursor
+    let _ = (os.st.ConsoleOut.EnableCursor)(os.st.ConsoleOut, false);
+
+    let (page_phys, func, args) = crate::main(&mut os);
+
+    unsafe {
+        kernel_entry(
+            page_phys,
+            args.stack_base
+                + args.stack_size
+                + if crate::KERNEL_64BIT {
+                    crate::arch::x64::PHYS_OFFSET
+                } else {
+                    crate::arch::x32::PHYS_OFFSET as u64
+                },
+            func,
+            &args,
+        );
+    }
+}
+
+pub fn disable_interrupts() {
+    unsafe {
+        asm!("cli");
+    }
+}

src/os/uefi/device.rs

@@ -0,0 +1,509 @@
+use alloc::{string::String, vec, vec::Vec};
+use core::{fmt::Write, mem, ptr, slice};
+use uefi::{
+    Handle,
+    device::{
+        DevicePath, DevicePathAcpiType, DevicePathBbsType, DevicePathEndType,
+        DevicePathHardwareType, DevicePathMediaType, DevicePathMessagingType, DevicePathType,
+    },
+    guid::Guid,
+    status::Status,
+};
+use uefi_std::{fs::FileSystem, loaded_image::LoadedImage, proto::Protocol};
+
+use super::disk::{DiskEfi, DiskOrFileEfi};
+
+#[derive(Debug)]
+enum DevicePathRelation {
+    This,
+    Parent(usize),
+    Child(usize),
+    None,
+}
+
+fn device_path_relation(a_path: &DevicePath, b_path: &DevicePath) -> DevicePathRelation {
+    let mut a_iter = DevicePathIter::new(a_path);
+    let mut b_iter = DevicePathIter::new(b_path);
+    loop {
+        match (a_iter.next(), b_iter.next()) {
+            (None, None) => return DevicePathRelation::This,
+            (None, Some(_)) => return DevicePathRelation::Parent(b_iter.count()),
+            (Some(_), None) => return DevicePathRelation::Child(a_iter.count()),
+            (Some((a_node, a_data)), Some((b_node, b_data))) => {
+                if a_node.Type != b_node.Type {
+                    return DevicePathRelation::None;
+                }
+
+                if a_node.SubType != b_node.SubType {
+                    return DevicePathRelation::None;
+                }
+
+                if a_data != b_data {
+                    return DevicePathRelation::None;
+                }
+            }
+        }
+    }
+}
+
+fn esp_live_image(esp_handle: Handle, esp_device_path: &DevicePath) -> Option<Vec<u8>> {
+    let mut esp_fs = match FileSystem::handle_protocol(esp_handle) {
+        Ok(esp_fs) => esp_fs,
+        Err(err) => {
+            log::warn!("Failed to find SimpleFileSystem protocol: {:?}", err);
+            return None;
+        }
+    };
+
+    let mut root = match esp_fs.root() {
+        Ok(root) => root,
+        Err(err) => {
+            log::warn!("Failed to open ESP filesystem: {:?}", err);
+            return None;
+        }
+    };
+
+    const fn as_utf16_str<const N: usize>(s: [u8; N]) -> [u16; N] {
+        let mut ret = [0; N];
+        let mut i = 0;
+        while i < N {
+            ret[i] = s[i] as u16;
+            i += 1;
+        }
+        ret
+    }
+
+    let filename = const { &as_utf16_str(*b"redox-live.iso\0") };
+    let mut live_image = match root.open(filename) {
+        Ok(live_image) => live_image,
+        Err(Status::NOT_FOUND) => return None,
+        Err(err) => {
+            log::warn!(
+                "Failed to open {}\\redox-live.iso: {:?}",
+                device_path_to_string(esp_device_path),
+                err
+            );
+            return None;
+        }
+    };
+
+    let mut buffer = Vec::new();
+
+    live_image.read_to_end(&mut buffer).unwrap();
+
+    Some(buffer)
+}
+
+pub struct DiskDevice {
+    pub handle: Handle,
+    pub disk: DiskOrFileEfi,
+    pub partition_offset: u64,
+    pub device_path: DevicePathProtocol,
+    pub file_path: Option<&'static str>,
+}
+
+pub fn disk_device_priority() -> Vec<DiskDevice> {
+    // Get the handle of the partition this program was loaded from, which should be the ESP
+    let esp_handle = match LoadedImage::handle_protocol(std::handle()) {
+        Ok(loaded_image) => loaded_image.0.DeviceHandle,
+        Err(err) => {
+            log::warn!("Failed to find LoadedImage protocol: {:?}", err);
+            return Vec::new();
+        }
+    };
+
+    // Get the device path of the ESP
+    let esp_device_path = match DevicePathProtocol::handle_protocol(esp_handle) {
+        Ok(ok) => ok,
+        Err(err) => {
+            log::warn!(
+                "Failed to find device path protocol on {:?}: {:?}",
+                esp_handle,
+                err
+            );
+            return Vec::new();
+        }
+    };
+
+    if cfg!(feature = "live") {
+        // First try to get a live image from redox-live.iso. This is required to support netbooting.
+        if let Some(buffer) = esp_live_image(esp_handle, esp_device_path.0) {
+            return vec![DiskDevice {
+                handle: esp_handle,
+                // Support both a copy of livedisk.iso and a standalone redoxfs partition
+                partition_offset: if &buffer[512..520] == b"EFI PART" {
+                    //TODO: get block from partition table
+                    2 * crate::MIBI as u64
+                } else {
+                    0
+                },
+                disk: DiskOrFileEfi::File(buffer),
+                device_path: esp_device_path,
+                file_path: Some("redox-live.iso"),
+            }];
+        }
+    }
+
+    // Get all block I/O handles along with their block I/O implementations and device paths
+    let handles = match DiskEfi::locate_handle() {
+        Ok(ok) => ok,
+        Err(err) => {
+            log::warn!("Failed to find block I/O handles: {:?}", err);
+            Vec::new()
+        }
+    };
+    let mut devices = Vec::with_capacity(handles.len());
+    for handle in handles {
+        let disk = match DiskEfi::handle_protocol(handle) {
+            Ok(ok) => ok,
+            Err(err) => {
+                log::warn!(
+                    "Failed to find block I/O protocol on {:?}: {:?}",
+                    handle,
+                    err
+                );
+                continue;
+            }
+        };
+
+        if !disk.0.Media.MediaPresent {
+            continue;
+        }
+
+        let device_path = match DevicePathProtocol::handle_protocol(handle) {
+            Ok(ok) => ok,
+            Err(err) => {
+                log::warn!(
+                    "Failed to find device path protocol on {:?}: {:?}",
+                    handle,
+                    err
+                );
+                continue;
+            }
+        };
+
+        devices.push(DiskDevice {
+            handle,
+            partition_offset: if disk.0.Media.LogicalPartition {
+                0
+            } else {
+                //TODO: get block from partition table
+                2 * crate::MIBI as u64
+            },
+            disk: DiskOrFileEfi::Disk(disk),
+            device_path,
+            file_path: None,
+        });
+    }
+
+    // Find possible boot disks
+    let mut boot_disks = Vec::with_capacity(1);
+    {
+        let mut i = 0;
+        while i < devices.len() {
+            if let DevicePathRelation::Parent(0) =
+                device_path_relation(devices[i].device_path.0, esp_device_path.0)
+            {
+                boot_disks.push(devices.remove(i));
+                continue;
+            }
+
+            i += 1;
+        }
+    }
+
+    // Find all children of possible boot devices
+    let mut priority = Vec::with_capacity(devices.capacity());
+    for boot_disk in boot_disks {
+        let mut i = 0;
+        while i < devices.len() {
+            // Only prioritize non-ESP devices
+            if devices[i].handle != esp_handle {
+                if let DevicePathRelation::Child(0) =
+                    device_path_relation(devices[i].device_path.0, boot_disk.device_path.0)
+                {
+                    priority.push(devices.remove(i));
+                    continue;
+                }
+            }
+
+            i += 1;
+        }
+
+        priority.push(boot_disk);
+    }
+
+    // Add any remaining devices
+    priority.extend(devices);
+
+    priority
+}
+
+#[repr(C, packed)]
+#[allow(dead_code)]
+struct DevicePathHarddrive {
+    partition_number: u32,
+    partition_start: u64,
+    partition_size: u64,
+    partition_signature: [u8; 16],
+    partition_format: u8,
+    signature_type: u8,
+}
+
+pub fn device_path_to_string(device_path: &DevicePath) -> String {
+    let mut s = String::new();
+    for (node, node_data) in DevicePathIter::new(device_path) {
+        let read_u16 = |i: usize| -> u16 { (node_data[i] as u16) | (node_data[i + 1] as u16) << 8 };
+
+        let read_u32 = |i: usize| -> u32 {
+            (node_data[i] as u32)
+                | (node_data[i + 1] as u32) << 8
+                | (node_data[i + 2] as u32) << 16
+                | (node_data[i + 3] as u32) << 24
+        };
+
+        if !s.is_empty() {
+            s.push('/');
+        }
+
+        let _ = match DevicePathType::try_from(node.Type) {
+            Ok(path_type) => match path_type {
+                DevicePathType::Hardware => match DevicePathHardwareType::try_from(node.SubType) {
+                    Ok(sub_type) => match sub_type {
+                        DevicePathHardwareType::Pci if node_data.len() == 2 => {
+                            let func = node_data[0];
+                            let dev = node_data[1];
+                            write!(s, "Pci(0x{dev:X},0x{func:X})")
+                        }
+                        _ => write!(s, "{path_type:?} {sub_type:?} {node_data:X?}"),
+                    },
+                    Err(()) => write!(s, "{:?} 0x{:02X} {:X?}", path_type, node.SubType, node_data),
+                },
+                DevicePathType::Acpi => match DevicePathAcpiType::try_from(node.SubType) {
+                    Ok(sub_type) => match sub_type {
+                        DevicePathAcpiType::Acpi if node_data.len() == 8 => {
+                            let hid = read_u32(0);
+                            let uid = read_u32(4);
+                            if hid & 0xFFFF == 0x41D0 {
+                                write!(s, "Acpi(PNP{:04X},0x{:X})", hid >> 16, uid)
+                            } else {
+                                write!(s, "Acpi(0x{hid:08X},0x{uid:X})")
+                            }
+                        }
+                        _ => write!(s, "{path_type:?} {sub_type:?} {node_data:X?}"),
+                    },
+                    Err(()) => write!(s, "{:?} 0x{:02X} {:X?}", path_type, node.SubType, node_data),
+                },
+                DevicePathType::Messaging => {
+                    match DevicePathMessagingType::try_from(node.SubType) {
+                        Ok(sub_type) => match sub_type {
+                            DevicePathMessagingType::Sata if node_data.len() == 6 => {
+                                let hba_port = read_u16(0);
+                                let multiplier_port = read_u16(2);
+                                let logical_unit = read_u16(4);
+                                if multiplier_port & (1 << 15) != 0 {
+                                    write!(s, "Sata(0x{hba_port:X},0x{logical_unit:X})")
+                                } else {
+                                    write!(
+                                        s,
+                                        "Sata(0x{hba_port:X},0x{multiplier_port:X},0x{logical_unit:X})"
+                                    )
+                                }
+                            }
+                            DevicePathMessagingType::Usb if node_data.len() == 2 => {
+                                let port = node_data[0];
+                                let iface = node_data[1];
+                                write!(s, "Usb(0x{port:X},0x{iface:X})")
+                            }
+                            DevicePathMessagingType::Nvme if node_data.len() == 12 => {
+                                let nsid = read_u32(0);
+                                let eui = &node_data[4..];
+                                if eui == [0, 0, 0, 0, 0, 0, 0, 0] {
+                                    write!(s, "NVMe(0x{nsid:X})")
+                                } else {
+                                    write!(
+                                        s,
+                                        "NVMe(0x{:X},{:02X}-{:02X}-{:02X}-{:02X}-{:02X}-{:02X}-{:02X}-{:02X})",
+                                        nsid,
+                                        eui[0],
+                                        eui[1],
+                                        eui[2],
+                                        eui[3],
+                                        eui[4],
+                                        eui[5],
+                                        eui[6],
+                                        eui[7],
+                                    )
+                                }
+                            }
+                            DevicePathMessagingType::Mac
+                                if node_data.len() == 33 && node_data[32] == 0
+                                    || node_data[32] == 1 =>
+                            {
+                                write!(
+                                    s,
+                                    "Mac({:02x}{:02x}{:02x}{:02x}{:02x}{:02x},{:#02x})",
+                                    node_data[0],
+                                    node_data[1],
+                                    node_data[2],
+                                    node_data[3],
+                                    node_data[4],
+                                    node_data[5],
+                                    node_data[32],
+                                )
+                            }
+                            _ => write!(s, "{path_type:?} {sub_type:?} {node_data:X?}"),
+                        },
+                        Err(()) => {
+                            write!(s, "{:?} 0x{:02X} {:X?}", path_type, node.SubType, node_data)
+                        }
+                    }
+                }
+                DevicePathType::Media => match DevicePathMediaType::try_from(node.SubType) {
+                    Ok(sub_type) => {
+                        match sub_type {
+                            DevicePathMediaType::Harddrive
+                                if node_data.len() == mem::size_of::<DevicePathHarddrive>() =>
+                            {
+                                let harddrive = unsafe {
+                                    ptr::read(node_data.as_ptr() as *const DevicePathHarddrive)
+                                };
+                                let partition_number = unsafe {
+                                    ptr::read_unaligned(ptr::addr_of!(harddrive.partition_number))
+                                };
+                                match harddrive.signature_type {
+                                    1 => {
+                                        let id = unsafe {
+                                            ptr::read(harddrive.partition_signature.as_ptr()
+                                                as *const u32)
+                                        };
+                                        write!(s, "HD(0x{partition_number:X},MBR,0x{id:X})")
+                                    }
+                                    2 => {
+                                        let guid = unsafe {
+                                            ptr::read(harddrive.partition_signature.as_ptr()
+                                                as *const Guid)
+                                        };
+                                        write!(
+                                            s,
+                                            "HD(0x{:X},GPT,{:08X}-{:04X}-{:04X}-{:02X}{:02X}-{:02X}{:02X}{:02X}{:02X}{:02X}{:02X})",
+                                            partition_number,
+                                            guid.0,
+                                            guid.1,
+                                            guid.2,
+                                            guid.3[0],
+                                            guid.3[1],
+                                            guid.3[2],
+                                            guid.3[3],
+                                            guid.3[4],
+                                            guid.3[5],
+                                            guid.3[6],
+                                            guid.3[7],
+                                        )
+                                    }
+                                    _ => {
+                                        write!(
+                                            s,
+                                            "HD(0x{:X},0x{:X},{:X?})",
+                                            partition_number,
+                                            harddrive.signature_type,
+                                            harddrive.partition_signature
+                                        )
+                                    }
+                                }
+                            }
+                            DevicePathMediaType::Filepath => {
+                                for chunk in node_data.chunks_exact(2) {
+                                    let data = (chunk[0] as u16) | (chunk[1] as u16) << 8;
+                                    match unsafe { char::from_u32_unchecked(data as u32) } {
+                                        '\\' => s.push('/'),
+                                        c => s.push(c),
+                                    }
+                                }
+                                Ok(())
+                            }
+                            _ => write!(s, "{path_type:?} {sub_type:?} {node_data:X?}"),
+                        }
+                    }
+                    Err(()) => write!(s, "{:?} 0x{:02X} {:X?}", path_type, node.SubType, node_data),
+                },
+                DevicePathType::Bbs => match DevicePathBbsType::try_from(node.SubType) {
+                    Ok(sub_type) => write!(s, "{path_type:?} {sub_type:?} {node_data:X?}"),
+                    Err(()) => write!(s, "{:?} 0x{:02X} {:X?}", path_type, node.SubType, node_data),
+                },
+                DevicePathType::End => match DevicePathEndType::try_from(node.SubType) {
+                    Ok(sub_type) => write!(s, "{path_type:?} {sub_type:?} {node_data:X?}"),
+                    Err(()) => write!(s, "{:?} 0x{:02X} {:X?}", path_type, node.SubType, node_data),
+                },
+            },
+            Err(()) => {
+                write!(
+                    s,
+                    "0x{:02X} 0x{:02X} {:X?}",
+                    node.Type, node.SubType, node_data
+                )
+            }
+        };
+    }
+    s
+}
+
+pub struct DevicePathProtocol(pub &'static mut DevicePath);
+
+impl Protocol<DevicePath> for DevicePathProtocol {
+    fn guid() -> Guid {
+        uefi::guid::DEVICE_PATH_GUID
+    }
+
+    fn new(inner: &'static mut DevicePath) -> Self {
+        Self(inner)
+    }
+}
+
+pub struct LoadedImageDevicePathProtocol(pub &'static mut DevicePath);
+
+impl Protocol<DevicePath> for LoadedImageDevicePathProtocol {
+    fn guid() -> Guid {
+        uefi::guid::LOADED_IMAGE_DEVICE_PATH_GUID
+    }
+
+    fn new(inner: &'static mut DevicePath) -> Self {
+        Self(inner)
+    }
+}
+
+pub struct DevicePathIter<'a> {
+    device_path: &'a DevicePath,
+    node_ptr: *const DevicePath,
+}
+
+impl<'a> DevicePathIter<'a> {
+    pub fn new(device_path: &'a DevicePath) -> Self {
+        Self {
+            device_path,
+            node_ptr: device_path as *const DevicePath,
+        }
+    }
+}
+
+impl<'a> Iterator for DevicePathIter<'a> {
+    type Item = (&'a DevicePath, &'a [u8]);
+    fn next(&mut self) -> Option<Self::Item> {
+        let node = unsafe { &*self.node_ptr };
+
+        if node.Type == DevicePathType::End as u8 {
+            return None;
+        }
+
+        let node_data = unsafe {
+            slice::from_raw_parts(
+                self.node_ptr.add(1) as *mut u8,
+                node.Length.saturating_sub(4) as usize,
+            )
+        };
+
+        self.node_ptr = (self.node_ptr as usize + node.Length as usize) as *const DevicePath;
+
+        Some((node, node_data))
+    }
+}

src/os/uefi/disk.rs

@@ -0,0 +1,119 @@
+use alloc::vec::Vec;
+use core::slice;
+use redoxfs::{BLOCK_SIZE, Disk, RECORD_SIZE};
+use std::proto::Protocol;
+use syscall::{EINVAL, EIO, Error, Result};
+use uefi::block_io::BlockIo as UefiBlockIo;
+use uefi::guid::{BLOCK_IO_GUID, Guid};
+
+pub enum DiskOrFileEfi {
+    Disk(DiskEfi),
+    File(Vec<u8>),
+}
+
+impl redoxfs::Disk for DiskOrFileEfi {
+    unsafe fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> syscall::Result<usize> {
+        unsafe {
+            match self {
+                DiskOrFileEfi::Disk(disk_efi) => disk_efi.read_at(block, buffer),
+                DiskOrFileEfi::File(data) => {
+                    buffer.copy_from_slice(
+                        &data[(block * redoxfs::BLOCK_SIZE) as usize
+                            ..(block * redoxfs::BLOCK_SIZE) as usize + buffer.len()],
+                    );
+                    Ok(buffer.len())
+                }
+            }
+        }
+    }
+
+    unsafe fn write_at(&mut self, _block: u64, _buffer: &[u8]) -> syscall::Result<usize> {
+        unreachable!()
+    }
+
+    fn size(&mut self) -> syscall::Result<u64> {
+        unreachable!()
+    }
+}
+
+pub struct DiskEfi(pub &'static mut UefiBlockIo, &'static mut [u8]);
+
+impl Protocol<UefiBlockIo> for DiskEfi {
+    fn guid() -> Guid {
+        BLOCK_IO_GUID
+    }
+
+    fn new(inner: &'static mut UefiBlockIo) -> Self {
+        // Hack to get aligned buffer
+        let block = unsafe {
+            let ptr = super::alloc_zeroed_page_aligned(RECORD_SIZE as usize);
+            slice::from_raw_parts_mut(ptr, RECORD_SIZE as usize)
+        };
+
+        Self(inner, block)
+    }
+}
+
+impl Disk for DiskEfi {
+    unsafe fn read_at(&mut self, block: u64, buffer: &mut [u8]) -> Result<usize> {
+        unsafe {
+            // Optimization for live disks
+            if let Some(live) = crate::LIVE_OPT {
+                if block >= live.0 {
+                    let start = ((block - live.0) * BLOCK_SIZE) as usize;
+                    let end = start + buffer.len();
+                    if end <= live.1.len() {
+                        buffer.copy_from_slice(&live.1[start..end]);
+                        return Ok(buffer.len());
+                    }
+                }
+            }
+
+            // Use aligned buffer if necessary
+            let mut ptr = buffer.as_mut_ptr();
+            if self.0.Media.IoAlign != 0 {
+                if (ptr as usize) % (self.0.Media.IoAlign as usize) != 0 {
+                    if buffer.len() <= self.1.len() {
+                        ptr = self.1.as_mut_ptr();
+                    } else {
+                        println!(
+                            "DiskEfi::read_at 0x{:X} requires alignment, ptr = 0x{:p}, len = 0x{:x}",
+                            block,
+                            ptr,
+                            buffer.len()
+                        );
+                        return Err(Error::new(EINVAL));
+                    }
+                }
+            }
+
+            let block_size = self.0.Media.BlockSize as u64;
+            let lba = block * BLOCK_SIZE / block_size;
+
+            match (self.0.ReadBlocks)(self.0, self.0.Media.MediaId, lba, buffer.len(), ptr) {
+                status if status.is_success() => {
+                    // Copy to original buffer if using aligned buffer
+                    if ptr != buffer.as_mut_ptr() {
+                        let (left, _) = self.1.split_at(buffer.len());
+                        buffer.copy_from_slice(left);
+                    }
+                    Ok(buffer.len())
+                }
+                err => {
+                    println!("DiskEfi::read_at 0x{:X} failed: {:?}", block, err);
+                    Err(Error::new(EIO))
+                }
+            }
+        }
+    }
+
+    unsafe fn write_at(&mut self, block: u64, _buffer: &[u8]) -> Result<usize> {
+        println!("DiskEfi::write_at 0x{:X} not implemented", block);
+        Err(Error::new(EIO))
+    }
+
+    fn size(&mut self) -> Result<u64> {
+        println!("DiskEfi::size not implemented");
+        Err(Error::new(EIO))
+    }
+}

src/os/uefi/display.rs

@@ -0,0 +1,41 @@
+use std::proto::Protocol;
+use uefi::graphics::GraphicsOutput;
+use uefi::guid::{GRAPHICS_OUTPUT_PROTOCOL_GUID, Guid};
+
+pub struct Output(pub &'static mut GraphicsOutput);
+
+impl Protocol<GraphicsOutput> for Output {
+    fn guid() -> Guid {
+        GRAPHICS_OUTPUT_PROTOCOL_GUID
+    }
+
+    fn new(inner: &'static mut GraphicsOutput) -> Self {
+        Output(inner)
+    }
+}
+
+const EDID_ACTIVE_PROTOCOL_GUID: Guid = Guid(
+    0xbd8c1056,
+    0x9f36,
+    0x44ec,
+    [0x92, 0xa8, 0xa6, 0x33, 0x7f, 0x81, 0x79, 0x86],
+);
+
+#[allow(non_snake_case)]
+#[repr(C)]
+pub struct EdidActiveProtocol {
+    pub SizeOfEdid: u32,
+    pub Edid: *const u8,
+}
+
+pub struct EdidActive(pub &'static mut EdidActiveProtocol);
+
+impl Protocol<EdidActiveProtocol> for EdidActive {
+    fn guid() -> Guid {
+        EDID_ACTIVE_PROTOCOL_GUID
+    }
+
+    fn new(inner: &'static mut EdidActiveProtocol) -> Self {
+        EdidActive(inner)
+    }
+}

src/os/uefi/dtb.rs

@@ -0,0 +1,125 @@
+use crate::Os;
+use alloc::vec::Vec;
+use byteorder::BE;
+use byteorder::ByteOrder;
+use core::slice;
+use fdt::Fdt;
+use uefi::guid::DEVICE_TREE_GUID;
+#[cfg(target_arch = "aarch64")]
+use uefi::{
+    guid::SMBIOS3_TABLE_GUID,
+    status::{Result, Status},
+};
+
+pub static mut DEV_MEM_AREA: Vec<(usize, usize)> = Vec::new();
+
+pub unsafe fn is_in_dev_mem_region(addr: usize) -> bool {
+    #[allow(static_mut_refs)]
+    unsafe {
+        if DEV_MEM_AREA.is_empty() {
+            return false;
+        }
+        for item in DEV_MEM_AREA.iter() {
+            if (addr >= item.0) && (addr < item.0 + item.1) {
+                return true;
+            }
+        }
+        return false;
+    }
+}
+
+unsafe fn get_dev_mem_region(fdt: &Fdt) {
+    unsafe {
+        let Some(soc) = fdt.find_node("/soc") else {
+            return;
+        };
+        let Some(ranges) = soc.ranges() else {
+            return;
+        };
+        let cell_sizes = soc.cell_sizes();
+        for chunk in ranges {
+            let child_bus_addr = chunk.child_bus_address;
+            let parent_bus_addr = chunk.parent_bus_address;
+            let addr_size = chunk.size;
+            println!(
+                "dev mem 0x{:08x} 0x{:08x} 0x{:08x}",
+                child_bus_addr, parent_bus_addr, addr_size
+            );
+            #[allow(static_mut_refs)]
+            DEV_MEM_AREA.push((parent_bus_addr as usize, addr_size as usize));
+        }
+    }
+}
+
+fn parse_dtb(os: &impl Os, address: *const u8) -> Option<(u64, u64)> {
+    unsafe {
+        if let Ok(fdt) = fdt::Fdt::from_ptr(address) {
+            let mut rsdps_area = Vec::new();
+            //println!("DTB model = {}", fdt.root().model());
+            get_dev_mem_region(&fdt);
+            let length = fdt.total_size();
+            let align = 8;
+            rsdps_area.extend(core::slice::from_raw_parts(address, length));
+            rsdps_area.resize(((rsdps_area.len() + (align - 1)) / align) * align, 0u8);
+            let size = rsdps_area.len();
+            let base = os.alloc_zeroed_page_aligned(size);
+            slice::from_raw_parts_mut(base, size).copy_from_slice(&rsdps_area);
+            Some((base as u64, size as u64))
+        } else {
+            println!("Failed to parse DTB");
+            None
+        }
+    }
+}
+
+#[cfg(target_arch = "aarch64")]
+fn find_smbios3_system(address: *const u8) -> Result<dmidecode::System<'static>> {
+    unsafe {
+        let smb = core::slice::from_raw_parts(address, 24);
+        if let Ok(smbios) = dmidecode::EntryPoint::search(smb) {
+            let smb_structure_data = core::slice::from_raw_parts(
+                smbios.smbios_address() as *const u8,
+                smbios.smbios_len() as usize,
+            );
+            for structure in smbios.structures(smb_structure_data) {
+                if let Ok(sval) = structure {
+                    //println!("SMBIOS: {:#?}", sval);
+                    if let dmidecode::Structure::System(buf) = sval {
+                        return Ok(buf);
+                    }
+                }
+            }
+        }
+    }
+    Err(Status::NOT_FOUND)
+}
+
+pub(crate) fn find_dtb(os: &impl Os) -> Option<(u64, u64)> {
+    let cfg_tables = std::system_table().config_tables();
+    for cfg_table in cfg_tables.iter() {
+        if cfg_table.VendorGuid == DEVICE_TREE_GUID {
+            let addr = cfg_table.VendorTable;
+            return parse_dtb(os, addr as *const u8);
+        }
+    }
+
+    /* This hack is no longer needed, but can be re-enabled for testing
+    #[cfg(target_arch = "aarch64")]
+    for cfg_table in cfg_tables.iter() {
+        if cfg_table.VendorGuid == SMBIOS3_TABLE_GUID {
+            let addr = cfg_table.VendorTable;
+            if let Ok(sys) = find_smbios3_system(addr as *const u8) {
+                let get_dtb_addr = match (sys.manufacturer, sys.version) {
+                    ("QEMU", version) if version.starts_with("virt") => Some(0x4000_0000 as usize),
+                    _ => None,
+                };
+                if let Some(dtb_addr) = get_dtb_addr {
+                    return parse_dtb(os, dtb_addr as *const u8);
+                }
+            }
+        }
+    }
+    */
+
+    None
+}

src/os/uefi/memory_map.rs

@@ -0,0 +1,141 @@
+use alloc::vec;
+use alloc::vec::Vec;
+use core::{mem, ptr};
+use uefi::memory::{MemoryDescriptor, MemoryType};
+
+use crate::area_add;
+use crate::os::{OsMemoryEntry, OsMemoryKind};
+
+use super::status_to_result;
+
+pub struct MemoryMapIter {
+    map: Vec<u8>,
+    map_key: usize,
+    descriptor_size: usize,
+    descriptor_version: u32,
+    i: usize,
+}
+
+impl MemoryMapIter {
+    pub fn new() -> Self {
+        let uefi = std::system_table();
+
+        let mut map = vec![0; 65536];
+        let mut map_size = map.len();
+        let mut map_key = 0;
+        let mut descriptor_size = 0;
+        let mut descriptor_version = 0;
+        status_to_result((uefi.BootServices.GetMemoryMap)(
+            &mut map_size,
+            map.as_mut_ptr() as *mut MemoryDescriptor,
+            &mut map_key,
+            &mut descriptor_size,
+            &mut descriptor_version,
+        ))
+        .expect("Failed to get UEFI memory map");
+
+        // Ensure descriptor size is usable
+        assert!(descriptor_size >= mem::size_of::<MemoryDescriptor>());
+
+        // Ensure descriptor version is supported
+        assert_eq!(descriptor_version, 1);
+
+        // Reduce map size to returned value
+        map.truncate(map_size);
+
+        Self {
+            map,
+            map_key,
+            descriptor_size,
+            descriptor_version,
+            i: 0,
+        }
+    }
+
+    pub fn exit_boot_services(mut self) {
+        let handle = std::handle();
+        let uefi = std::system_table();
+
+        // We are writing to the memory map that will be passed to
+        // SetVirtualAddressMap before ExitBootServices as on some firmware
+        // EfiLoaderData memory regions like this one are marked as read-only
+        // after ExitBootServices
+        for i in 0..self.map.len() / self.descriptor_size {
+            let descriptor_ptr = unsafe { self.map.as_mut_ptr().add(i * self.descriptor_size) };
+            let descriptor = unsafe { &mut *(descriptor_ptr as *mut MemoryDescriptor) };
+
+            // Map all memory regions even when not marked as EFI_MEMORY_RUNTIME
+            // as some firmware uses memory regions not marked as
+            // EFI_MEMORY_RUNTIME in runtime services. Linux has a list of
+            // exactly which memory regions need to be mapped, but for simplicity
+            // we are mapping all regions here.
+
+            // Identity map all memory regions as some firmware fails to update
+            // all pointers in SetVirtualAddressMap.
+
+            descriptor.VirtualStart.0 = descriptor.PhysicalStart.0;
+        }
+
+        status_to_result((uefi.BootServices.ExitBootServices)(handle, self.map_key))
+            .expect("Failed to exit UEFI boot services");
+
+        // Runtime services must be called with interrupts disabled
+        super::arch::disable_interrupts();
+
+        status_to_result((uefi.RuntimeServices.SetVirtualAddressMap)(
+            self.map.len(),
+            self.descriptor_size,
+            self.descriptor_version,
+            self.map.as_ptr() as *const MemoryDescriptor,
+        ))
+        .expect("Failed to set UEFI runtime services virtual address map");
+
+        // After ExitBootServices, GlobalAlloc::dealloc() is not allowed anymore
+        // as it uses boot services.
+        mem::forget(self);
+    }
+}
+
+impl Iterator for MemoryMapIter {
+    type Item = OsMemoryEntry;
+    fn next(&mut self) -> Option<Self::Item> {
+        if self.i < self.map.len() / self.descriptor_size {
+            let descriptor_ptr = unsafe { self.map.as_ptr().add(self.i * self.descriptor_size) };
+            self.i += 1;
+
+            let descriptor = unsafe { ptr::read(descriptor_ptr as *const MemoryDescriptor) };
+            let descriptor_type: MemoryType = unsafe { mem::transmute(descriptor.Type) };
+
+            Some(OsMemoryEntry {
+                base: descriptor.PhysicalStart.0,
+                //TODO: do not hard code page size
+                size: descriptor.NumberOfPages * 4096,
+                kind: match descriptor_type {
+                    MemoryType::EfiLoaderCode
+                    | MemoryType::EfiLoaderData
+                    | MemoryType::EfiBootServicesCode
+                    | MemoryType::EfiBootServicesData
+                    | MemoryType::EfiConventionalMemory => OsMemoryKind::Free,
+                    //TODO: mark ACPI memory as reclaim
+                    _ => OsMemoryKind::Reserved,
+                },
+            })
+        } else {
+            None
+        }
+    }
+}
+
+pub unsafe fn memory_map() -> MemoryMapIter {
+    let mut iter = MemoryMapIter::new();
+
+    // Using next to avoid consuming iterator
+    while let Some(entry) = iter.next() {
+        area_add(entry);
+    }
+
+    // Rewind iterator
+    iter.i = 0;
+
+    iter
+}

src/os/uefi/mod.rs

@@ -0,0 +1,396 @@
+use alloc::vec::Vec;
+use core::{cell::RefCell, mem, ptr, slice};
+use std::proto::Protocol;
+use uefi::{
+    Handle,
+    boot::LocateSearchType,
+    memory::MemoryType,
+    reset::ResetType,
+    status::{Result, Status},
+    system::SystemTable,
+    text::TextInputKey,
+};
+
+use crate::os::{Os, OsHwDesc, OsKey, OsVideoMode};
+
+use self::{
+    device::{device_path_to_string, disk_device_priority},
+    disk::DiskOrFileEfi,
+    display::{EdidActive, Output},
+    video_mode::VideoModeIter,
+};
+
+mod acpi;
+mod arch;
+mod device;
+mod disk;
+mod display;
+#[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
+pub mod dtb;
+mod memory_map;
+mod video_mode;
+
+#[cfg(target_arch = "riscv64")]
+pub use arch::efi_get_boot_hartid;
+
+pub(crate) fn page_size() -> usize {
+    // EDK2 always uses 4096 as the page size
+    4096
+}
+
+pub(crate) fn alloc_zeroed_page_aligned(size: usize) -> *mut u8 {
+    assert!(size != 0);
+
+    let page_size = page_size();
+    let pages = size.div_ceil(page_size);
+
+    let ptr = {
+        // Max address mapped by src/arch paging code (8 GiB)
+        let mut ptr = 0x2_0000_0000;
+        status_to_result((std::system_table().BootServices.AllocatePages)(
+            1,                                  // AllocateMaxAddress
+            MemoryType::EfiRuntimeServicesData, // Keeps this memory out of free space list
+            pages,
+            &mut ptr,
+        ))
+        .unwrap();
+        ptr as *mut u8
+    };
+
+    assert!(!ptr.is_null());
+    unsafe { ptr::write_bytes(ptr, 0, pages * page_size) };
+    ptr
+}
+
+pub struct OsEfi {
+    st: &'static SystemTable,
+    outputs: RefCell<Vec<(Output, Option<EdidActive>)>>,
+}
+
+impl OsEfi {
+    pub fn new() -> Self {
+        let st = std::system_table();
+        let mut outputs = Vec::<(Output, Option<EdidActive>)>::new();
+        {
+            let guid = Output::guid();
+            let mut handles = Vec::with_capacity(256);
+            let mut len = handles.capacity() * mem::size_of::<Handle>();
+            match status_to_result((st.BootServices.LocateHandle)(
+                LocateSearchType::ByProtocol,
+                &guid,
+                ptr::null(),
+                &mut len,
+                handles.as_mut_ptr(),
+            )) {
+                Ok(_) => {
+                    unsafe {
+                        handles.set_len(len / mem::size_of::<Handle>());
+                    }
+                    'handles: for handle in handles {
+                        //TODO: do we have to query all modes to get good edid?
+                        match Output::handle_protocol(handle) {
+                            Ok(output) => {
+                                log::debug!(
+                                    "Output {:?} at {:x}",
+                                    handle,
+                                    output.0.Mode.FrameBufferBase
+                                );
+
+                                if output.0.Mode.FrameBufferBase == 0 {
+                                    log::debug!("Skipping output with frame buffer base of 0");
+                                    continue 'handles;
+                                }
+
+                                for other_output in outputs.iter() {
+                                    if output.0.Mode.FrameBufferBase
+                                        == other_output.0.0.Mode.FrameBufferBase
+                                    {
+                                        log::debug!(
+                                            "Skipping output with frame buffer base matching another output"
+                                        );
+                                        continue 'handles;
+                                    }
+                                }
+
+                                outputs.push((
+                                    output,
+                                    match EdidActive::handle_protocol(handle) {
+                                        Ok(efi_edid) => Some(efi_edid),
+                                        Err(err) => {
+                                            log::warn!(
+                                                "Failed to get EFI EDID from handle {:?}: {:?}",
+                                                handle,
+                                                err
+                                            );
+                                            None
+                                        }
+                                    },
+                                ));
+                            }
+                            Err(err) => {
+                                log::warn!(
+                                    "Failed to get Output from handle {:?}: {:?}",
+                                    handle,
+                                    err
+                                );
+                            }
+                        }
+                    }
+                }
+                Err(err) => {
+                    log::warn!("Failed to locate Outputs: {:?}", err);
+                }
+            }
+        }
+        Self {
+            st,
+            outputs: RefCell::new(outputs),
+        }
+    }
+}
+
+impl Os for OsEfi {
+    type D = DiskOrFileEfi;
+    type V = VideoModeIter;
+
+    #[cfg(target_arch = "aarch64")]
+    fn name(&self) -> &str {
+        "aarch64/UEFI"
+    }
+
+    #[cfg(target_arch = "x86_64")]
+    fn name(&self) -> &str {
+        "x86_64/UEFI"
+    }
+
+    #[cfg(target_arch = "riscv64")]
+    fn name(&self) -> &str {
+        "riscv64/UEFI"
+    }
+
+    fn alloc_zeroed_page_aligned(&self, size: usize) -> *mut u8 {
+        alloc_zeroed_page_aligned(size)
+    }
+
+    fn page_size(&self) -> usize {
+        page_size()
+    }
+
+    fn filesystem(
+        &self,
+        password_opt: Option<&[u8]>,
+    ) -> syscall::Result<redoxfs::FileSystem<DiskOrFileEfi>> {
+        // Search for RedoxFS on disks in prioritized order
+        println!("Looking for RedoxFS:");
+        for device in disk_device_priority() {
+            if let Some(file_path) = device.file_path {
+                log::debug!(
+                    " - {}\\{}",
+                    device_path_to_string(device.device_path.0),
+                    file_path
+                );
+            } else {
+                log::debug!(" - {}", device_path_to_string(device.device_path.0));
+            }
+
+            let block = device.partition_offset / redoxfs::BLOCK_SIZE;
+
+            match redoxfs::FileSystem::open(device.disk, password_opt, Some(block), false) {
+                Ok(ok) => return Ok(ok),
+                Err(err) => match err.errno {
+                    // Ignore header not found error
+                    syscall::ENOENT => (),
+                    // Print any other errors
+                    _ => {
+                        log::warn!("BlockIo error: {:?}", err);
+                    }
+                },
+            }
+        }
+
+        log::warn!("No RedoxFS partitions found");
+        Err(syscall::Error::new(syscall::ENOENT))
+    }
+
+    fn hwdesc(&self) -> OsHwDesc {
+        //TODO: if both DTB and ACPI are found, we should probably let the OS choose what to use?
+
+        // For now we will prefer DTB on platforms that have it
+        #[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))]
+        if let Some((addr, size)) = dtb::find_dtb(self) {
+            return OsHwDesc::DeviceTree(addr, size);
+        }
+
+        if let Some((addr, size)) = acpi::find_acpi_table_pointers(self) {
+            return OsHwDesc::Acpi(addr, size);
+        }
+
+        OsHwDesc::NotFound
+    }
+
+    fn video_outputs(&self) -> usize {
+        self.outputs.borrow().len()
+    }
+
+    fn video_modes(&self, output_i: usize) -> VideoModeIter {
+        let output_opt = match self.outputs.borrow_mut().get_mut(output_i) {
+            Some(output) => unsafe {
+                // Hack to enable clone
+                let ptr = output.0.0 as *mut _;
+                Some(Output::new(&mut *ptr))
+            },
+            None => None,
+        };
+        VideoModeIter::new(output_opt)
+    }
+
+    fn set_video_mode(&self, output_i: usize, mode: &mut OsVideoMode) {
+        //TODO: return error?
+        let mut outputs = self.outputs.borrow_mut();
+        let (output, _efi_edid_opt) = &mut outputs[output_i];
+        status_to_result((output.0.SetMode)(output.0, mode.id)).unwrap();
+
+        // Update with actual mode information
+        mode.width = output.0.Mode.Info.HorizontalResolution;
+        mode.height = output.0.Mode.Info.VerticalResolution;
+        mode.base = output.0.Mode.FrameBufferBase as u64;
+    }
+
+    fn best_resolution(&self, output_i: usize) -> Option<(u32, u32)> {
+        let mut outputs = self.outputs.borrow_mut();
+        let (output, efi_edid_opt) = outputs.get_mut(output_i)?;
+
+        if let Some(efi_edid) = efi_edid_opt {
+            let edid =
+                unsafe { slice::from_raw_parts(efi_edid.0.Edid, efi_edid.0.SizeOfEdid as usize) };
+
+            if edid.len() > 0x3D {
+                return Some((
+                    (edid[0x38] as u32) | (((edid[0x3A] as u32) & 0xF0) << 4),
+                    (edid[0x3B] as u32) | (((edid[0x3D] as u32) & 0xF0) << 4),
+                ));
+            } else {
+                log::warn!("EFI EDID too small: {}", edid.len());
+            }
+        }
+
+        // Fallback to the current output resolution
+        Some((
+            output.0.Mode.Info.HorizontalResolution,
+            output.0.Mode.Info.VerticalResolution,
+        ))
+    }
+
+    fn get_key(&self) -> OsKey {
+        //TODO: do not unwrap
+
+        let mut index = 0;
+        status_to_result((self.st.BootServices.WaitForEvent)(
+            1,
+            &self.st.ConsoleIn.WaitForKey,
+            &mut index,
+        ))
+        .unwrap();
+
+        let mut key = TextInputKey {
+            ScanCode: 0,
+            UnicodeChar: 0,
+        };
+        status_to_result((self.st.ConsoleIn.ReadKeyStroke)(
+            self.st.ConsoleIn,
+            &mut key,
+        ))
+        .unwrap();
+
+        match key.ScanCode {
+            0 => match key.UnicodeChar {
+                8 => OsKey::Backspace,
+                13 => OsKey::Enter,
+                w => match char::from_u32(w as u32) {
+                    Some(c) => OsKey::Char(c),
+                    None => OsKey::Other,
+                },
+            },
+            1 => OsKey::Up,
+            2 => OsKey::Down,
+            3 => OsKey::Right,
+            4 => OsKey::Left,
+            8 => OsKey::Delete,
+            _ => OsKey::Other,
+        }
+    }
+
+    fn clear_text(&self) {
+        //TODO: why does this sometimes return InvalidParameter, but otherwise appear to work?
+        let _ = status_to_result((self.st.ConsoleOut.ClearScreen)(self.st.ConsoleOut));
+    }
+
+    fn get_text_position(&self) -> (usize, usize) {
+        (
+            self.st.ConsoleOut.Mode.CursorColumn as usize,
+            self.st.ConsoleOut.Mode.CursorRow as usize,
+        )
+    }
+
+    fn set_text_position(&self, x: usize, y: usize) {
+        // Ignore error because Tow-Boot appears to not implement this
+        let _ = status_to_result((self.st.ConsoleOut.SetCursorPosition)(
+            self.st.ConsoleOut,
+            x,
+            y,
+        ));
+    }
+
+    fn set_text_highlight(&self, highlight: bool) {
+        let attr = if highlight { 0x70 } else { 0x07 };
+        status_to_result((self.st.ConsoleOut.SetAttribute)(self.st.ConsoleOut, attr)).unwrap();
+    }
+}
+
+fn status_to_result(status: Status) -> Result<usize> {
+    match status {
+        Status(ok) if status.is_success() => Ok(ok),
+        err => Err(err),
+    }
+}
+
+fn set_max_mode(output: &uefi::text::TextOutput) -> Result<()> {
+    let mut max_i = None;
+    let mut max_w = 0;
+    let mut max_h = 0;
+
+    for i in 0..output.Mode.MaxMode as usize {
+        let mut w = 0;
+        let mut h = 0;
+        if (output.QueryMode)(output, i, &mut w, &mut h).is_success() {
+            if w >= max_w && h >= max_h {
+                max_i = Some(i);
+                max_w = w;
+                max_h = h;
+            }
+        }
+    }
+
+    if let Some(i) = max_i {
+        status_to_result((output.SetMode)(output, i))?;
+    }
+
+    Ok(())
+}
+
+#[unsafe(no_mangle)]
+pub extern "C" fn main() -> Status {
+    let uefi = std::system_table();
+
+    let _ = (uefi.BootServices.SetWatchdogTimer)(0, 0, 0, ptr::null());
+
+    if let Err(err) = set_max_mode(uefi.ConsoleOut) {
+        println!("Failed to set max mode: {:?}", err);
+    }
+
+    if let Err(err) = arch::main() {
+        panic!("App error: {:?}", err);
+    }
+
+    (uefi.RuntimeServices.ResetSystem)(ResetType::Cold, Status(0), 0, ptr::null());
+}

src/os/uefi/video_mode.rs

@@ -0,0 +1,57 @@
+use core::ptr;
+use log::error;
+use uefi::status::Status;
+
+use crate::os::OsVideoMode;
+use crate::os::uefi::display::Output;
+
+pub struct VideoModeIter {
+    output_opt: Option<Output>,
+    i: u32,
+}
+
+impl VideoModeIter {
+    pub fn new(output_opt: Option<Output>) -> Self {
+        Self { output_opt, i: 0 }
+    }
+}
+
+impl Iterator for VideoModeIter {
+    type Item = OsVideoMode;
+    fn next(&mut self) -> Option<Self::Item> {
+        if let Some(ref mut output) = self.output_opt {
+            while self.i < output.0.Mode.MaxMode {
+                let id = self.i;
+                self.i += 1;
+
+                let mut mode_ptr = ::core::ptr::null_mut();
+                let mut mode_size = 0;
+                match (output.0.QueryMode)(output.0, id, &mut mode_size, &mut mode_ptr) {
+                    Status::SUCCESS => (),
+                    err => {
+                        error!("Failed to read mode {}: {:?}", id, err);
+                        continue;
+                    }
+                }
+
+                //TODO: ensure mode_size is set correctly
+                let mode = unsafe { ptr::read(mode_ptr) };
+
+                let width = mode.HorizontalResolution;
+                let height = mode.VerticalResolution;
+                let stride = mode.PixelsPerScanLine;
+
+                return Some(OsVideoMode {
+                    id,
+                    width,
+                    height,
+                    stride,
+                    // Base is retrieved later by setting the mode
+                    base: 0,
+                });
+            }
+        }
+
+        None
+    }
+}

src/serial_16550.rs

@@ -0,0 +1,142 @@
+use bitflags::bitflags;
+use core::convert::TryInto;
+use core::fmt;
+use core::ptr::{addr_of, addr_of_mut};
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+use syscall::io::Pio;
+use syscall::io::{Io, Mmio, ReadOnly};
+
+bitflags! {
+    /// Interrupt enable flags
+    struct IntEnFlags: u8 {
+        const RECEIVED = 1;
+        const SENT = 1 << 1;
+        const ERRORED = 1 << 2;
+        const STATUS_CHANGE = 1 << 3;
+        // 4 to 7 are unused
+    }
+}
+
+bitflags! {
+    /// Line status flags
+    struct LineStsFlags: u8 {
+        const INPUT_FULL = 1;
+        // 1 to 4 unknown
+        const OUTPUT_EMPTY = 1 << 5;
+        // 6 and 7 unknown
+    }
+}
+
+#[allow(dead_code)]
+#[repr(C, packed)]
+pub struct SerialPort<T: Io> {
+    /// Data register, read to receive, write to send
+    data: T,
+    /// Interrupt enable
+    int_en: T,
+    /// FIFO control
+    fifo_ctrl: T,
+    /// Line control
+    line_ctrl: T,
+    /// Modem control
+    modem_ctrl: T,
+    /// Line status
+    line_sts: ReadOnly<T>,
+    /// Modem status
+    modem_sts: ReadOnly<T>,
+}
+
+#[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
+impl SerialPort<Pio<u8>> {
+    pub const fn new(base: u16) -> SerialPort<Pio<u8>> {
+        SerialPort {
+            data: Pio::new(base),
+            int_en: Pio::new(base + 1),
+            fifo_ctrl: Pio::new(base + 2),
+            line_ctrl: Pio::new(base + 3),
+            modem_ctrl: Pio::new(base + 4),
+            line_sts: ReadOnly::new(Pio::new(base + 5)),
+            modem_sts: ReadOnly::new(Pio::new(base + 6)),
+        }
+    }
+}
+
+impl SerialPort<Mmio<u32>> {
+    pub unsafe fn new(base: usize) -> &'static mut SerialPort<Mmio<u32>> {
+        unsafe { &mut *(base as *mut Self) }
+    }
+}
+
+impl<T: Io> SerialPort<T>
+where
+    T::Value: From<u8> + TryInto<u8>,
+{
+    pub fn init(&mut self) {
+        unsafe {
+            //TODO: Cleanup
+            // FIXME: Fix UB if unaligned
+            (*addr_of_mut!(self.int_en)).write(0x00.into());
+            (*addr_of_mut!(self.line_ctrl)).write(0x80.into());
+            (*addr_of_mut!(self.data)).write(0x01.into());
+            (*addr_of_mut!(self.int_en)).write(0x00.into());
+            (*addr_of_mut!(self.line_ctrl)).write(0x03.into());
+            (*addr_of_mut!(self.fifo_ctrl)).write(0xC7.into());
+            (*addr_of_mut!(self.modem_ctrl)).write(0x0B.into());
+            (*addr_of_mut!(self.int_en)).write(0x01.into());
+        }
+    }
+
+    fn line_sts(&self) -> LineStsFlags {
+        LineStsFlags::from_bits_truncate(
+            (unsafe { &*addr_of!(self.line_sts) }.read() & 0xFF.into())
+                .try_into()
+                .unwrap_or(0),
+        )
+    }
+
+    pub fn receive(&mut self) -> Option<u8> {
+        if self.line_sts().contains(LineStsFlags::INPUT_FULL) {
+            Some(
+                (unsafe { &*addr_of!(self.data) }.read() & 0xFF.into())
+                    .try_into()
+                    .unwrap_or(0),
+            )
+        } else {
+            None
+        }
+    }
+
+    pub fn send(&mut self, data: u8) {
+        while !self.line_sts().contains(LineStsFlags::OUTPUT_EMPTY) {}
+        unsafe { &mut *addr_of_mut!(self.data) }.write(data.into())
+    }
+
+    pub fn write(&mut self, buf: &[u8]) {
+        for &b in buf {
+            match b {
+                8 | 0x7F => {
+                    self.send(8);
+                    self.send(b' ');
+                    self.send(8);
+                }
+                b'\n' => {
+                    self.send(b'\r');
+                    self.send(b'\n');
+                }
+                _ => {
+                    self.send(b);
+                }
+            }
+        }
+    }
+}
+
+impl<T: Io> fmt::Write for SerialPort<T>
+where
+    T::Value: From<u8> + TryInto<u8>,
+{
+    fn write_str(&mut self, s: &str) -> Result<(), fmt::Error> {
+        self.write(s.as_bytes());
+        Ok(())
+    }
+}

targets/aarch64-unknown-uefi.json

@@ -0,0 +1,25 @@
+{
+  "arch": "aarch64",
+  "data-layout": "e-m:e-i64:64-f80:128-n8:16:32:64-S128",
+  "default-hidden-visibility": true,
+  "emit-debug-gdb-scripts": false,
+  "exe-suffix": ".efi",
+  "executables": true,
+  "is-like-windows": true,
+  "linker": "rust-lld",
+  "linker-flavor": "lld-link",
+  "llvm-target": "aarch64-pc-windows-msvc",
+  "os": "uefi",
+  "panic-strategy": "abort",
+  "pre-link-args": {
+    "lld-link": [
+      "/subsystem:EFI_Application",
+      "/entry:efi_main",
+      "/machine:arm64"
+    ]
+  },
+  "stack_probes": true,
+  "target-c-int-width": 32,
+  "target-endian": "little",
+  "target-pointer-width": 64
+}

targets/riscv64gc-unknown-uefi.json

@@ -0,0 +1,25 @@
+{
+  "arch": "riscv64",
+  "code-model": "medium",
+  "cpu": "generic-rv64",
+  "data-layout": "e-m:e-p:64:64-i64:64-i128:128-n32:64-S128",
+  "emit-debug-gdb-scripts": false,
+  "exe-suffix": ".elf",
+  "executables": true,
+  "linker-flavor": "gnu-cc",
+  "linker": "riscv64-unknown-redox-gcc",
+  "llvm-abiname": "lp64d",
+  "features": "+m,+a,+f,+d,+c",
+  "llvm-target": "riscv64-unknown-none-elf",
+  "os": "none",
+  "metadata": {
+    "description": null,
+    "host_tools": null,
+    "std": null,
+    "tier": null
+  },
+  "panic-strategy": "abort",
+  "target-c-int-width": 32,
+  "target-endian": "little",
+  "target-pointer-width": 64
+}

targets/x86-unknown-none.json

@@ -0,0 +1,29 @@
+{
+    "llvm-target": "i686-unknown-none",
+    "target-endian": "little",
+    "target-pointer-width": 32,
+    "target-c-int-width": 32,
+    "data-layout": "e-m:e-p:32:32-p270:32:32-p271:32:32-p272:64:64-i128:128-f64:32:64-f80:32-n8:16:32-S128",
+    "arch": "x86",
+    "os": "none",
+    "env": "",
+    "vendor": "unknown",
+    "linker-flavor": "gcc",
+    "panic-strategy": "abort",
+    "pre-link-args": {
+        "gcc": ["-m32", "-nostdlib", "-static"]
+    },
+    "features": "-mmx,-sse,-sse2,-sse3,-ssse3,-sse4.1,-sse4.2,-avx,-avx2,+soft-float",
+    "rustc-abi": "x86-softfloat",
+    "dynamic-linking": false,
+    "executables": false,
+    "relocation-model": "static",
+    "code-model": "large",
+    "disable-redzone": true,
+    "frame-pointer": "always",
+    "exe-suffix": "",
+    "has-rpath": false,
+    "no-default-libraries": true,
+    "position-independent-executables": false,
+    "tls-model": "global-dynamic"
+}