Red Bear OS
d24d0e2174
Phase G.2 of the ACPI/Arrow Lake port. The LG Gram 2025 (Core Ultra 7
255H, Arrow Lake-H) uses Intel HWP for P-state control — legacy
IA32_PERF_CTL writes are silently ignored when HWP is active.
The previous cpufreqd always wrote IA32_PERF_CTL (MSR 0x199), which
on Arrow Lake-H had zero effect. We now:
1. Detect HWP at startup by reading IA32_PM_ENABLE (MSR 0x770) bit 0
2. If HWP is active:
a. Read IA32_HWP_CAPABILITIES (MSR 0x771) for the
min/max/guaranteed/efficient performance range
b. Translate the governor's P-state index into the HWP
"Desired Performance" field + EPP hint
c. Write IA32_HWP_REQUEST (MSR 0x774) instead of IA32_PERF_CTL
3. If HWP is not active, fall back to the legacy IA32_PERF_CTL path
(preserves backward compatibility for older CPUs)
The kernel's new /scheme/sys/msr/ scheme (Phase G.1) provides the
in-memory storage backing the MSR reads/writes. On the real LG Gram
2025 hardware, the kernel's MSR scheme will be wired to the actual
hardware MSRs (Phase G+ work); the cpufreqd interface is unchanged.
HWP layout (Intel SDM Vol 3B §14.4.4):
[7:0] Minimum Performance
[15:8] Maximum Performance
[23:16] Desired Performance
[31:24] Energy-Performance Preference (EPP)
[42:32] Activity Window (0 = auto)
[42] Package Control
EPP follows the same index as desired perf: 0 = performance,
255 = power-save. We map the linear P-state index to both the
"Desired Performance" and EPP so the H/W sees a single hint that
the OS wants both the performance and energy level it implies.
Includes:
- PstateMode enum (LegacyPerfCtl | Hwp) for compile-time dispatch
- detect_pstate_mode() reads MSR 0x770
- read_hwp_capabilities() reads MSR 0x771, returns (min, max,
guaranteed, efficient) bytes
- hwp_request_for() maps P-state index to IA32_HWP_REQUEST u64
- apply_pstate() dispatches to the right MSR based on ci.mode
- The /scheme/cpufreq/state output now tags each CPU with [HWP] or
[legacy] for observability
Hardware test plan: on the LG Gram 2025, "performance" governor
should pin IA32_HWP_REQUEST.Desired = hwp_max with EPP=0; "powersave"
should pin it to hwp_min with EPP=255; "ondemand" should ramp
between. Reading IA32_PERF_STATUS (MSR 0x198) via /scheme/sys/msr
should reflect the new operating point within ~1ms.
Red Bear OS
A microkernel operating system written in Rust, derived from Redox OS
What is Red Bear OS?
Red Bear OS is a general-purpose, Unix-like operating system with a microkernel architecture, written in Rust. It is a full fork of Redox OS, frozen at release 0.1.0, with added hardware support, filesystem drivers, and a KDE Plasma desktop path.
Goals:
- AMD & Intel parity — first-class support for both platforms on bare metal
- KDE Plasma desktop — Wayland-based desktop environment via the KWin compositor
- Hardware GPU acceleration — AMD GPU (amdgpu) and Intel GPU drivers via
redox-drm - Modern subsystems — USB, Wi‑Fi, Bluetooth, ext4, GRUB, D-Bus
- Offline-first builds — reproducible from archived, BLAKE3-verified sources
Our Git Server
Red Bear OS lives on a self-hosted Gitea instance at https://gitea.redbearos.org. This is the canonical home for the fork — there is no GitHub / GitLab / Codeberg mirror that is authoritative.
| Field | Value |
|---|---|
| Host | https://gitea.redbearos.org |
| User | vasilito |
| Token | (session-only — never stored in repo) |
| Web UI | https://gitea.redbearos.org/vasilito |
| Main repo | https://gitea.redbearos.org/vasilito/RedBear-OS |
Token policy. The
vasilitotoken is a per-session credential and must never be committed to any tracked file. Usegit credential.helper(store / cache / libsecret),~/.netrc, or$REDBEAR_GITEA_TOKENenv var. Seelocal/AGENTS.md§ Our Git Server for the full operator runbook, mirror list, API reference, and recovery procedure.
Quick Start
Prerequisites
Linux x86_64 host with Rust nightly, QEMU, nasm, and standard build tools.
See the Redox Build Guide for full setup.
Build & Run
# Clone (read-only)
git clone https://gitea.redbearos.org/vasilito/RedBear-OS.git
cd RedBear-OS
# Authenticated clone (one-off) — supply token via env var, not literal here
git clone https://vasilito:${REDBEAR_GITEA_TOKEN}@gitea.redbearos.org/vasilito/RedBear-OS.git
# Recommended: use the Red Bear wrapper
./local/scripts/build-redbear.sh redbear-mini # Text-only target
./local/scripts/build-redbear.sh redbear-full # Desktop-capable target
# Boot in QEMU with the resulting image
make qemu
Build script:
local/scripts/build-redbear.shis the canonical entry point. Baremake allworks but bypasses the.configchecking andREDBEAR_ALLOW_PROTECTED_FETCH=1gates thatbuild-redbear.shenforces. SeeAGENTS.md§ Build Commands for full details.
Public Scripts
| Script | Purpose |
|---|---|
local/scripts/build-redbear.sh |
Canonical build wrapper for redbear-mini/full/grub |
scripts/run.sh |
Build and run in QEMU (-b to build, -c <config> for target) |
scripts/build-iso.sh |
Build a live ISO for bare-metal boot |
scripts/build-all-isos.sh |
Build all live ISO targets |
scripts/network-boot.sh |
PXE network boot helper |
scripts/dual-boot.sh |
Dual-boot installation helper |
Config Targets
| Target | Type | Description |
|---|---|---|
redbear-full |
Desktop | Wayland + KDE + GPU drivers + D-Bus services |
redbear-mini |
Console | Text-only recovery / install target |
redbear-grub |
Console | Text-only with GRUB boot manager |
Current Status
Red Bear OS boots to a login prompt in QEMU with working wired networking, D-Bus system bus, hardware detection daemons, and filesystem support (RedoxFS, ext4, FAT).
| Area | Status |
|---|---|
| Boot (ACPI/x2APIC/SMP) | ✅ Bare-metal proven |
| Userspace drivers (PCI, storage, net) | ✅ Working in QEMU |
| D-Bus system bus + services | ✅ Working (login1, PolicyKit, UDisks, UPower) |
| ext4 / FAT filesystems | ✅ Compiles, installer-wired |
| POSIX gaps (relibc) | 🚧 Bounded Wayland-facing support |
| DRM/KMS display drivers | 🚧 AMD + Intel compile; HW validation pending |
| Wayland compositor | 🚧 Bounded proof; Qt6/KF6 clients crash at init |
| KDE Plasma desktop | 🔄 In progress (Qt6/KF6 compile; KWin/QML blocked) |
| Wi‑Fi / Bluetooth | 📋 Planned (architected, implementation pending) |
How It Works
Red Bear OS uses a userspace driver model — all drivers run as unprivileged daemons:
Kernel (microkernel)
└── schemes: memory, irq, event, pipe, debug
└── Driver daemons (userspace)
├── pcid → PCI enumeration
├── e1000d → Intel ethernet
├── xhcid → USB controller
└── vesad → Display framebuffer
The kernel provides minimal services (memory, interrupts, IPC). Everything else — filesystems, networking, graphics, input — runs in userspace.
Documentation
- Implementation Plan — roadmap and execution model
- Desktop Path Plan — kernel → DRM → Mesa → Wayland → KDE
- D-Bus Integration — session bus architecture
- USB Plan — USB stack design
- Wi‑Fi Plan — wireless architecture
- Bluetooth Plan — BT stack design
- Documentation Index — full doc map
Contributing
Red Bear OS uses a full fork model. Upstream Redox sources are frozen and archived. All custom work lives in local/:
local/
├── patches/ # Durable changes to upstream source trees
├── recipes/ # Custom packages (drivers, GPU, system)
├── docs/ # Integration and planning docs
└── scripts/ # Build, test, and release tooling
We welcome contributions made with or without AI assistance — we care about quality, not how the code was produced.
License
MIT — same as upstream Redox OS.