Red Bear OS
2055dcdd44
Three improvements derived from running CachyOS 2026-06-28 in QEMU and comparing to the Red Bear OS boot sequence. drivers/pcid/src/main.rs: - PIIX4/PIIX5 IDE (vendor 0x8086, device 0x7010/0x7111) gets a 'fixed BAR' quirk that pins BAR0..3 to the legacy IDE IO ports (0x1F0/0x3F6/0x170/0x376) and BAR4 to the BM-DMA window (0xC0C0/0xC0C8). The standard QEMU firmware model ignores BAR programming and uses the legacy IO layout directly; without the fix the ided driver reads whatever happens to be in config space and misses the bus-master window. Linux applies the same quirk in drivers/ata/ata_piix.c. - Class 0x03 (display controller) devices now log a vgaarb-style 'setting as boot VGA device' message. On QEMU there's only the Bochs 1234:1111, so the arbitration is unambiguous; on real multi-GPU hardware the message makes the kernel's choice observable. Full scheme-level arbitration (a /scheme/system/vga returning the owner) is left for a future change. initfs/tools/Cargo.toml + initfs/tools/src/bin/loop_mnt.rs: - New loop_mnt binary that scans /scheme/initfs/etc/* for block devices and probes each for the RedoxFS magic. On the first match it writes the path to /scheme/runtime/loop_mnt_target, so that 50_rootfs.service / redoxfs can read the choice and fall back to the dynamic-discovery path that CachyOS's archiso_loop_mnt hook provides. The implementation is intentionally a no-op when no RedoxFS volume is found, so the explicit initfs.toml path remains the source of truth on a normal boot. init.initfs.d/45_loop_mnt.service: - Init service unit that invokes loop_mnt after pcid-spawner-initfs but with weak ordering so it never blocks the existing 50_rootfs path. Mirrors the CachyOS archiso_loop_mnt role without conflicting with the explicit initfs.toml flow. recipes/core/base-initfs/recipe.toml: - Cross-compile loop_mnt during the base-initfs build so the binary is present in the packed initfs image, and place it before the redox-initfs-ar archive step so the service file is included in the same image.
Drivers
- Libraries
- Services
- Hardware Interfaces
- Devices
- System Interfaces
- System Calls
- Schemes
- Contribution Details
Libraries
- amlserde - Library to provide serialization/deserialization of the AML symbol table from ACPI
- common - Library with shared driver code
- executor - Library to run Rust futures and integrate the executor in an interrupt+queue model without a separated reactor thread
- graphics/console-draw - Library with shared terminal drawing code
- graphics/driver-graphics - Library with shared graphics code
- graphics/graphics-ipc - Library with graphics IPC shared code
- net/driver-network - Library with shared networking code
- storage/partitionlib - Library with MBR and GPT code
- storage/driver-block - Library with shared storage code
- virtio-core - VirtIO driver library
Services
- graphics/fbbootlogd - Daemon for boot log drawing
- graphics/fbcond - Terminal daemon
- hwd - Daemon that handle the ACPI and DeviceTree booting
- inputd - Multiplexes input from multiple input drivers and provides that to Orbital
- pcid-spawner - Daemon for PCI-based device driver spawn
- storage/lived - Daemon for live disk
- redoxerd - Daemon that send/receive terminal text between the host system and QEMU
Hardware Interfaces
- acpid - ACPI interface driver
- pcid - PCI and PCI Express driver
Devices
CPU
- rtcd - x86 Real Time Clock driver
Controllers
- usb/xhcid - xHCI USB controller driver
Storage
- storage/ahcid - AHCI (SATA) driver
- storage/bcm2835-sdhcid - BCM2835 storage driver
- storage/ided - PATA (IDE) driver
- storage/nvmed - NVMe driver
- storage/virtio-blkd - VirtIO block device driver
- storage/usbscsid - USB SCSI driver
Graphics
- graphics/ihdgd - Intel graphics driver
- graphics/vesad - VESA video driver
- graphics/virtio-gpud - VirtIO-GPU device driver
Input
- input/ps2d - PS/2 interface driver
- input/usbhidd - USB HID driver
- usb/usbhubd - USB Hub driver
- usb/usbctl - TODO
Sound
- audio/ac97d - AC'97 codec driver
- audio/ihdad - Intel HD Audio chipset driver
- audio/sb16d - Sound Blaster sound card driver
Networking
- net/e1000d - Intel Gigabit ethernet driver
- net/ixgbed - Intel 10 Gigabit ethernet driver
- net/rtl8139d, net/rtl8168d - Realtek ethernet drivers
- net/virtio-netd - VirtIO network device driver
Virtualization
- vboxd - VirtualBox driver
Some drivers are work-in-progress and incomplete, read this tracking issue to verify.
System Interfaces
This section explain the system interfaces used by drivers.
System Calls
iopl: system call that sets the I/O privilege level. x86 has four privilege rings (0/1/2/3), of which the kernel runs in ring 0 and userspace in ring 3. IOPL can only be changed by the kernel, for obvious security reasons, and therefore the Redox kernel needs root to set it. It is unique for each process. Processes with IOPL=3 can access I/O ports, and the kernel can access them as well.
Schemes
/scheme/memory/physical: Allows mapping physical memory frames to driver-accessible virtual memory pages, with various available memory types:/scheme/memory/physical: Default memory type (currently writeback)/scheme/memory/physical@wbWriteback cached memory/scheme/memory/physical@uc: Uncacheable memory/scheme/memory/physical@wc: Write-combining memory
/scheme/irq: Allows getting events from interrupts. It is used primarily by listening for its file descriptors using the/scheme/eventscheme.
Contribution Details
Driver Design
A device driver on Redox is an user-space daemon that use system calls and schemes to work, while operating systems with monolithic kernels drivers use internal kernel APIs instead of common program APIs.
If you want to port a driver from a monolithic operating system to Redox you will need to rewrite the driver with reverse enginnering of the code logic, because the logic is adapted to internal kernel APIs (it's a hard task if the device is complex, datasheets are much more easy).
Write a Driver
Datasheets are preferable (much more easy depending on device complexity), when they are freely available. Be aware that datasheets are often provided under a Non-Disclosure Agreement from hardware vendors, which can affect the ability to create an MIT-licensed driver.
If datasheets aren't available you need to do reverse-engineering of BSD or Linux drivers (if you want use a Linux driver as reference for your Redox driver please ask in the Chat before the implementation to know/satisfy the license requirements and not waste your time, also if you use a BSD driver not licensed as BSD as reference).
Libraries
You should use the redox-scheme and redox_event libraries to create your drivers, you can also read the example driver or read the code of other drivers with the same type of your device.
Before testing your changes be aware of this.
References
If you want to reverse enginner the existing drivers, you can access the BSD code using these links:
How To Contribute
To learn how to contribute to this system component you need to read the following document:
Development
To learn how to do development with this system component inside the Redox build system you need to read the Build System and Coding and Building pages.
How To Build
To build this system component you need to download the Redox build system, you can learn how to do it on the Building Redox page.
This is necessary because they only work with cross-compilation to a Redox virtual machine or real hardware, but you can do some testing from Linux.