RedBear-OS/local/docs/ACPI-FIXES.md

ACPI Fixes — P0 Phase Tracker

Numbering note: "P0" refers to the historical hardware-enablement phase (ACPI boot), not the v2.0 desktop plan phases in local/docs/CONSOLE-TO-KDE-DESKTOP-PLAN.md.

Status of ACPI fixes for AMD bare metal boot. Cross-referenced with HARDWARE.md crash reports and kernel/acpid source TODOs.

P0 ACPI work is complete. Kernel patch is 574 lines, base/acpid patch is 558 lines.

Crash Reports

Hardware	Symptom	Root Cause	Status
Framework Laptop 16 (AMD 7040)	Crash on boot	Unimplemented ACPI function (jackpot51/acpi#3)	✅ Fixed (RSDP/SDT checksums, MADT NMI types, FADT parse)
Lenovo ThinkCentre M83	Aml(NoCurrentOp) panic at acpid acpi.rs:256	AML interpreter encounters unsupported opcode	Under investigation (upstream AML issue)
HP Compaq nc6120	Crash after kernel::acpi prints APIC info	xAPIC APIC ID read returned raw value, caused page fault on Intel	✅ Fixed (xAPIC id() now shifts read(0x20) >> 24)

Known Missing ACPI Table Parsers

Table	Location	Status	Impact
DSDT (Differentiated System Description Table)	Parsed by acpi crate AML interpreter	Working	Platform-specific device config via AML bytecode
SSDT (Secondary System Description Table)	Parsed by acpi crate AML interpreter	Working	Secondary AML tables (hotplug, etc.)
FACP/FADT	✅ Full parse in acpid	✅ Done	PM registers, reset register, sleep states, \_S5
IVRS (AMD-Vi IOMMU)	Removed from acpid stub path	Handled by iommu daemon path	ACPI-side broken stub removed; runtime AMD-Vi handling now lives in the separate daemon
MCFG (PCI Express config space)	Removed (broken stub)	✅ Handled by pcid	pcid /config endpoint provides direct PCI config space access
DBG2 (Debug port)	Not implemented	Low	Serial debug port discovery
BGRT (Boot graphics)	Not implemented	Low	Boot logo preservation
FPDT (Firmware perf data)	Not implemented	Low	Boot performance metrics

IVRS was previously listed as "implemented" but the acpid stub was broken, so it was removed from acpid. AMD-Vi runtime handling now lives in the separate iommu daemon path rather than in acpid. MCFG is now handled by pcid's /config endpoint (P1 complete) which provides direct PCI config space access.

Implemented ACPI Tables

Table	Kernel	Userspace (acpid)	Notes
RSDP	acpi/rsdp.rs	N/A	Signature + checksum validated (ACPI 1.0 + 2.0+ extended)
RSDT/XSDT	acpi/rsdt.rs, acpi/xsdt.rs	N/A	Root table pointer iteration + SDT checksum validation
MADT (APIC)	acpi/madt/	N/A	xAPIC + x2APIC (type 0x9) + NMI (0x4, 0xA) + address override (0x5)
HPET	acpi/hpet.rs	N/A	Assumes single HPET
DMAR (Intel VT-d)	N/A	acpi/dmar/	Iterator bug fixed, re-enabled, safe on AMD (early return)
FADT	N/A	acpi.rs	Full: PM1a/b CNT, reset register, \_S5 sleep types, GenericAddress I/O
Power Methods	N/A	acpi.rs	\_PS0/\_PS3/\_PPC AML evaluation for device power control
SPCR	acpi/spcr.rs	N/A	ARM64 serial console
GTDT	acpi/gtdt.rs	N/A	ARM64 timers

ACPI MADT Entry Types

All MADT entry types parsed by the kernel. The MADT loop in x86.rs dispatches each type to the appropriate handler.

Type	Name	Struct	Size	Kernel Action
0x0	Processor Local APIC	MadtLocalApic	8 bytes	AP boot via SIPI
0x1	I/O APIC	MadtIoApic	12 bytes	Enumerated
0x2	Interrupt Source Override	MadtIntSrcOverride	10 bytes	IRQ remapping
0x4	Local APIC NMI	MadtLocalApicNmi	4 bytes	LVT NMI programming (xAPIC 0x350/0x360)
0x5	LAPIC Address Override	MadtLapicAddressOverride	10 bytes	Logged (64-bit address)
0x9	Local x2APIC	MadtLocalX2Apic	16 bytes	AP boot via x2APIC ICR (MSR)
0xA	Local x2APIC NMI	MadtLocalX2ApicNmi	10 bytes	x2APIC LVT NMI MSR (0x835/0x836)

All structs include compile-time size assertions (assert!(size_of::<T>() == N)) to catch ABI mismatches early.

Kernel ACPI TODOs

From recipes/core/kernel/source/src/acpi/:

File	Line	TODO	Priority
mod.rs	132	Don't touch ACPI tables in kernel? (move to userspace)	Future
mod.rs	147	Enumerate processors in userspace	Future
mod.rs	154	Let userspace setup HPET	Future
rsdp.rs	21	Validate RSDP checksum ✅ Done	P0 Done
hpet.rs	56	Assumes only one HPET	Low
spcr.rs	38,86,100,110	Optional fields, more interrupt types	ARM64 only
madt/mod.rs	134	Optional field in ACPI 6.5 (trbe_interrupt)	Low
madt/mod.rs	—	NMI entry parsing ✅ Done (types 0x4, 0xA)	P0 Done
madt/mod.rs	—	LVT NMI programming ✅ Done (xAPIC + x2APIC)	P0 Done
madt/mod.rs	—	LAPIC address override ✅ Done (type 0x5)	P0 Done
madt/mod.rs	—	xAPIC APIC ID fix ✅ Done (read(0x20) >> 24)	P0 Done
madt/mod.rs	—	SDT checksum validation ✅ Done (warn-only)	P0 Done

ACPID (Userspace) TODOs — UPSTREAM, NOT AMD-FIRST P0/P1

These are pre-existing upstream acpid issues. They are NOT part of the AMD-first P0/P1 scope. They exist in mainline Redox acpid and affect all platforms, not just AMD.

File	Line	TODO	Priority	Scope
acpi.rs	266	Use parsed tables for rest of acpid	Upstream	Mainline acpid improvement
acpi.rs	643	Handle SLP_TYPb for sleep states	Upstream	Mainline power management
aml_physmem.rs	418,423,428	Mutex create/acquire/release	Upstream	Mainline AML interpreter
ec.rs	193+ (8 occurrences)	Proper error types	Upstream	Mainline EC handler
dmar/mod.rs	7	Move DMAR to separate driver	Upstream	Mainline driver refactor

P0 Fixes Applied

Kernel ACPI (local/patches/kernel/redox.patch — 574 lines)

#	Fix	Description
1	xAPIC APIC ID fix	id() returns read(0x20) >> 24 for xAPIC mode (was raw, caused Intel page fault)
2	x2APIC MADT type 0x9	MadtLocalX2Apic struct + AP boot via ICR with universal startup algorithm
3	ICR pending wait	Pre/post wrmsr PENDING bit check for x2APIC set_icr()
4	ICR constants	ICR_INIT_ASSERT (0x4500), ICR_STARTUP (0x4600) with bit-layout comments
5	MADT entry length guard	entry_len < 2 returns None (prevents infinite loop on malformed tables)
6	RSDP checksum validation	ACPI 1.0 + 2.0+ extended checksum
7	SDT checksum validation	validate_checksum() method + warn-only on failure
8	CPUID arch split	Separate x86/x86_64 cpuid functions
9	Memory alignment	find_free_near_aligned() with power-of-two assert
10	Trampoline W+X	Documented limitation (code must be writable + executable during AP init)
11	MADT type 0x4 (Local APIC NMI)	MadtLocalApicNmi struct (4 bytes), compile-time size assertion
12	MADT type 0x5 (LAPIC Address Override)	MadtLapicAddressOverride struct (10 bytes), logged
13	MADT type 0xA (x2APIC NMI)	MadtLocalX2ApicNmi struct (10 bytes), compile-time size assertion
14	LVT NMI programming	set_lvt_nmi() method for xAPIC (0x350/0x360) and x2APIC (0x835/0x836 MSRs)
15	NMI processing in x86.rs	LocalApicNmi, LocalX2ApicNmi, LapicAddressOverride handling in MADT loop
16	AP startup timeout	100M-iteration bounded waits prevent infinite hang
17	Second SIPI	Universal Startup Algorithm compliance (Intel spec requires two SIPIs)

Userspace Acpid (local/patches/base/redox.patch — 558 lines)

#	Fix	Description
1	DMAR iterator fix	type_bytes renamed to len_bytes bug fix + len < 4 guard
2	DMAR init re-enabled	Safe on AMD (no DMAR table = early return, no crash)
3	FADT shutdown	acpi_shutdown() using PM1a/PM1b CNT_BLK writes with \_S5 sleep types
4	FADT reboot	acpi_reboot() using ACPI reset register via GenericAddress
5	Keyboard controller fallback	Pio::<u8>::new(0x64).write(0xFE) when reset_reg unavailable
6	Power methods	evaluate_acpi_method(), device_power_on() (\_PS0), device_power_off() (\_PS3), device_get_performance() (\_PPC)
7	GenericAddress rename	GenericAddressStructure renamed to GenericAddress with is_empty(), write_u8()
8	Reboot wiring	reboot_requested flag in main.rs, scheme path detection
9	ivrs/mcfg removed	Broken stub references eliminated (deferred to P2+, handled by pcid)