CachyOS Linux Kernels

Enhanced Linux kernels with improved performance, multiple CPU schedulers, and advanced optimizations.

## Table of Contents - [Overview](#overview) - [Kernel Variants & Schedulers](#kernel-variants--schedulers) - [Features](#features) - [Performance Optimizations](#performance-optimizations) - [CPU Enhancements](#cpu-enhancements) - [Networking](#networking) - [Filesystem & Memory](#filesystem--memory) - [Additional Features](#additional-features) - [CachyOS Repositories](#cachyos-repositories) - [Quick Installation](#quick-installation) - [Manual Installation](#manual-installation) - [CPU Compatibility Check](#cpu-compatibility-check) - [Repository Configuration](#repository-configuration) - [SCX Schedulers](#scx-schedulers) - [Other Distributions](#other-distributions) - [Support & Community](#support--community) - [Contributors](#contributors) ## Overview CachyOS provides a collection of enhanced Linux kernels designed for improved performance across different workloads. Kernels are built from the [CachyOS Linux](https://github.com/CachyOS/linux) fork (currently based on **Linux 7.1**), which merges topic branches on top of upstream stable releases. Our kernels feature multiple CPU schedulers, advanced compiler optimizations, and carefully selected patches to deliver better responsiveness and throughput. > [!NOTE] > All CachyOS kernels are available in multiple architecture optimizations: `x86-64`, `x86-64-v3`, `x86-64-v4`, and `znver4`. ## Kernel Variants & Schedulers Each scheduler is optimized for different use cases. We recommend testing each one to find the best fit for your specific requirements. ### Available Schedulers | Scheduler | Full Name | Package(s) | Best for... | Developer | | :--- | :--- | :--- | :--- | :--- | | **[BORE](https://github.com/firelzrd/bore-scheduler)** | **B**urst-**O**riented **R**esponse **E**nhancer | `linux-cachyos-bore`, `linux-cachyos-deckify`, `linux-cachyos-hardened`, `linux-cachyos-rt-bore` | Interactive workloads & gaming | [firelzrd](https://github.com/firelzrd) | | **[EEVDF](https://lwn.net/Articles/927530/)** | **E**arliest **E**ligible **V**irtual **D**eadline **F**irst | `linux-cachyos`, `linux-cachyos-eevdf`, `linux-cachyos-lts`, `linux-cachyos-server` | General-purpose computing | Peter Zijlstra | | **[BMQ](https://gitlab.com/alfredchen/linux-prjc)** | **B**it**M**ap **Q**ueue CPU Scheduler | `linux-cachyos-bmq` | Throughput-oriented workloads | [Alfred Chen](https://gitlab.com/alfredchen) | ### Specialized Variants - **`linux-cachyos`** - Default kernel: EEVDF scheduler with Clang Thin LTO and AutoFDO - **`linux-cachyos-rc`** - Release candidate kernel tracking the next upstream version - **`linux-cachyos-hardened`** - Security-focused kernel with hardening patches and the BORE scheduler - **`linux-cachyos-lts`** - Long Term Support version (currently 6.18) with EEVDF and Cachy Sauce - **`linux-cachyos-rt-bore`** - Real-time kernel with BORE scheduler integration - **`linux-cachyos-server`** - Server-optimized EEVDF configuration with lazy preemption - **`linux-cachyos-deckify`** - Handheld gaming variant with BORE scheduler, Steam Deck support, and MSI Claw driver ### Compiler Variants - **`linux-cachyos`** - Default optimized build using Clang Thin LTO with AutoFDO + Propeller profile-guided optimizations - **Scheduler-specific packages** (`linux-cachyos-bore`, `linux-cachyos-bmq`, `linux-cachyos-eevdf`, etc.) - GCC-compiled builds without LTO, focused on scheduler choice over compiler optimizations > [!TIP] > For detailed explanations of each kernel variant, visit our [Kernel Wiki](https://wiki.cachyos.org/features/kernel). ## Features The CachyOS kernel fork merges topic branches into each release. The current **Linux 7.1** base integrates fifteen topic branches (`amd-isp4`, `bbr3`, `cachy`, `cgroup-vram`, `drm-fair`, `fixes`, `hdmi`, `lenovo-wmi`, `mglru`, `preempt-ipi`, `sched-cluster`, `snd-codecs`, `t2`, `vesa-dsc-bpp`, and `vmalloc-free`) on top of upstream stable. ### Performance Optimizations - **Advanced Compilation**: Highly customizable PKGBUILD with support for both GCC and Clang compilers - **Link Time Optimization (LTO)**: Clang Thin LTO (v12) enabled by default on the main `linux-cachyos` package - **Distributed ThinLTO**: Support for distributed Clang ThinLTO builds to speed up kernel compilation - **Profile-Guided Optimization**: AutoFDO + Propeller profiling on the default kernel for optimal code generation ([Learn more](https://cachyos.org/blog/2411-kernel-autofdo/)) - **Kernel Control Flow Integrity (kCFI)**: Available when using LLVM for enhanced security - **Timer Frequency Options**: Configurable between 100Hz, 250Hz, 300Hz, 500Hz, 600Hz, 750Hz, and 1000Hz (default: 1000Hz) - **Architecture Optimizations**: Support for x86-64-v3, x86-64-v4, and AMD Zen4 specific builds - **Compiler Optimizations**: Advanced GCC flags including `-fivopts` and `-fmodulo-sched` - **PREEMPT_DYNAMIC**: Runtime-selectable preemption modes (full, lazy, voluntary, none) - **vmalloc Optimizations**: Bulk page freeing in `vfree()`, improved `vrealloc()` shrink/grow paths, and optimized contiguous range freeing ### CPU Enhancements - **Multiple Schedulers**: BORE, EEVDF, and BMQ schedulers for different workload optimization - **[POC Selector](https://github.com/firelzrd/poc-selector) v2.6.3**: Piece-Of-Cake fast idle CPU selector inspired by scx_cake, reducing wakeup latency - **Cluster-Aware Scheduling**: Improved load balancing for CPU clusters, including balancing between CPUs of identical capacity on hybrid architectures - **Preempt-IPI Optimizations**: Lower-latency SMP/IPI paths with preemption re-enabled before TLB flushes and streamlined `smp_call_function()` handling - **CachyOS Sauce**: Custom `CONFIG_CACHY` configuration with scheduler and system tweaks - **AMD P-State Enhancements**: Preferred Core support and latest amd-pstate improvements from linux-next - **Real-Time Support**: RT kernel builds available with BORE scheduler integration - **Low-Latency Optimizations**: Patches for improved responsiveness and reduced jitter - **sched/wait LIFO accept()**: Socket accept() processed in LIFO order for better cache efficiency - **Wakeup CPU Affinity**: Prefer the previous CPU for task wakeups to improve cache locality ### Networking - **[BBR3 TCP](https://github.com/google/bbr)**: BBRv3 congestion control available as a separate module alongside BBRv1 ### Filesystem & Memory - **ZFS Support**: Built-in ZFS filesystem support with pre-compiled modules - **NTFS Improvements**: Upstream NTFS driver fixes for MFT mirror validation, attribute bounds checking, and logfile handling - **MGLRU Enhancements**: Unified writeback reclaim statistics, simplified vmscan accounting, improved dirty writeback reactivation, and Cachy Sauce MM tuning (LRU-gen working set protection, compaction/watermark tweaks, hugepage reclaim) - **Transparent Hugepages**: `ADVISE` mode for shmem/tmpfs transparent hugepages - **NVIDIA Integration**: - Proprietary NVIDIA driver modules with patches - Open-source NVIDIA driver support - Ready-to-use modules in repository - **I/O Scheduler Improvements**: - Enhanced BFQ and mq-deadline performance - [ADIOS](https://github.com/firelzrd/adios) v3.2.0 multi-queue I/O scheduler support - **VRAM Cgroup (DMEM)**: Device memory controller for restricting GPU VRAM usage per cgroup, with protection limits, common-ancestor pool sharing, and Nouveau DMEM support ### Additional Features #### Hardware Support - **AMD ISP4**: AMD ISP 4 camera driver for supported platforms - **Gaming Hardware**: Steam Deck patches (Audio, HW Quirks, HID), ROG Ally support, MSI Claw HID driver (deckify), and EasySMX 05 Pro gamepad support - **Apple Hardware**: T2 MacBook support with apple-bce driver in staging - **ASUS Hardware**: Extended ASUS hardware compatibility patches, including ACP audio fixes for Vivobook 18 and TUF Gaming A14 (2026) - **Lenovo Hardware**: WMI battery charge limiting, GPU/CPU tunable attributes, capdata debugfs, and AMD PMC suspend delay for improved sleep/resume - **HP Hardware**: OMEN Slim (including 16t-an000) and OMEN MAX laptop support via hp-wmi - **Samsung Hardware**: Galaxy Book 4/5 series audio fixes via MAX98390 HDA codec support - **Graphics**: HDR support enabled, AMDGPU min_powercap override (`amdgpu_ignore_min_pcap`), and DRM fair GPU scheduling favoring interactive clients - **Display**: HDMI VRR on AMD (including PCON path and freesync-on-desktop), ALLM and passive VRR connector properties, VESA DSC bits-per-pixel parsing from EDID - **Audio Codecs**: AW88399 and MAX98390 HDA side codec support #### System Enhancements - **Multimedia**: v4l2loopback modules included by default - **Virtualization**: ACS Override support for VFIO/GPU passthrough - **Upstream Integration**: Cherry-picked patches from Clear Linux and linux-next > [!NOTE] > For comprehensive details about each kernel variant and their specific optimizations, visit our [Kernel Documentation](https://wiki.cachyos.org/features/kernel). ## CachyOS Repositories Our [repositories](https://mirror.cachyos.org/) contain optimized Arch Linux and CachyOS packages rebuilt with performance, stability, and security enhancements. ### Available Repository Tiers | Repository | Target CPUs | Package Coverage | Optimization Level | |------------|-------------|------------------|--------------------| | `znver4` | AMD Zen 4 & Zen 5 | Full package set | Zen4-specific optimizations | | `x86-64-v4` | Intel Xeon / Intel 11th | Full package set | AVX, AVX2, AVX512, SSE4.2, SSSE3 | | `x86-64-v3` | 2012 or newer | Full package set | AVX, AVX2, SSE4.2, SSSE3 | | `x86-64` | All x86-64 CPUs | Kernels only | Basic optimizations | ### Quick Installation **Automated Setup (Recommended)** Our installation script automatically detects your CPU and configures the optimal repositories: ```bash # Download and extract the installer curl -O https://mirror.cachyos.org/cachyos-repo.tar.xz tar xvf cachyos-repo.tar.xz && cd cachyos-repo # Run the automated installer sudo ./cachyos-repo.sh ``` **What the script does:** - Auto-detects your CPU architecture support - Configures appropriate repository tiers - Backs up your existing `pacman.conf` - Sets up GPG keys and mirrors For more information, visit our [GitHub](https://github.com/cachyos) or join our [Discord](https://discord.gg/cachyos-862292009423470592) community. ### Manual Installation **Step 1: Add CachyOS Signing Keys** ```bash sudo pacman-key --recv-keys F3B607488DB35A47 --keyserver keyserver.ubuntu.com sudo pacman-key --lsign-key F3B607488DB35A47 ``` **Step 2: Install Required Packages** ```bash sudo pacman -U \ 'https://mirror.cachyos.org/repo/x86_64/cachyos/cachyos-keyring-20240331-1-any.pkg.tar.zst' \ 'https://mirror.cachyos.org/repo/x86_64/cachyos/cachyos-mirrorlist-27-1-any.pkg.tar.zst' \ 'https://mirror.cachyos.org/repo/x86_64/cachyos/cachyos-v3-mirrorlist-27-1-any.pkg.tar.zst' \ 'https://mirror.cachyos.org/repo/x86_64/cachyos/cachyos-v4-mirrorlist-27-1-any.pkg.tar.zst' \ 'https://mirror.cachyos.org/repo/x86_64/cachyos/pacman-7.1.0.r9.g54d9411-5-x86_64.pkg.tar.zst' ``` > [!CAUTION] > **About CachyOS Pacman**: This installs a forked version of pacman with CachyOS-specific features like `INSTALLED_FROM` tracking and automatic architecture detection. While this provides enhanced functionality, it may cause compatibility warnings with standard Arch Linux workflows. > > **Alternative**: If you prefer to avoid the custom pacman, skip the `cachyos` repository and only use the optimized package repositories (`cachyos-v3`, `cachyos-v4`, `cachyos-extra`, etc.). **Rollback Instructions** If you need to revert to standard Arch repositories after using CachyOS pacman: ```bash sudo find /var/lib/pacman/local/ -type f -name "desc" -exec sed -i '/^%INSTALLED_DB%$/,+2d' {} \; ``` ### CPU Compatibility Check Before manually configuring repositories, verify your CPU's instruction set support. > [!NOTE] > Skip this step if using the automated installation script—it handles detection automatically. **Check Your CPU Support** ```bash /lib/ld-linux-x86-64.so.2 --help | grep supported ``` **Understanding the Output** Look for the `(supported, searched)` indicators: - ✅ **`x86-64-v4 (supported, searched)`** = CPU supports v4 instruction set - ❌ **`x86-64-v4`** (without parentheses) = CPU does NOT support v4 **Example Output for Compatible CPU:** ``` $ /lib/ld-linux-x86-64.so.2 --help | grep supported x86-64-v4 (supported, searched) x86-64-v3 (supported, searched) x86-64-v2 (supported, searched) ``` **Instruction Set Requirements:** - **x86-64-v4**: Intel Haswell (2013+) / AMD Excavator (2015+) - **x86-64-v3**: Intel Nehalem (2008+) / AMD Bulldozer (2011+) - **x86-64-v2**: Intel Core 2 (2006+) / AMD K8 (2003+) ### Repository Configuration Edit your pacman configuration to add the appropriate repositories: ```bash sudo nano /etc/pacman.conf ``` **For x86-64 (Basic) Support:** ```ini # CachyOS repositories [cachyos] Include = /etc/pacman.d/cachyos-mirrorlist ``` **For x86-64-v3 Support:** ```ini # CachyOS repositories (add in this order) [cachyos-v3] Include = /etc/pacman.d/cachyos-v3-mirrorlist [cachyos-core-v3] Include = /etc/pacman.d/cachyos-v3-mirrorlist [cachyos-extra-v3] Include = /etc/pacman.d/cachyos-v3-mirrorlist [cachyos] Include = /etc/pacman.d/cachyos-mirrorlist ``` **For x86-64-v4 Support:** ```ini # CachyOS repositories (add in this order) [cachyos-v4] Include = /etc/pacman.d/cachyos-v4-mirrorlist [cachyos-core-v4] Include = /etc/pacman.d/cachyos-v4-mirrorlist [cachyos-extra-v4] Include = /etc/pacman.d/cachyos-v4-mirrorlist [cachyos] Include = /etc/pacman.d/cachyos-mirrorlist ``` **For AMD Zen 4/5/6 CPUs:** ```ini # CachyOS repositories (Zen4 optimized) [cachyos-znver4] Include = /etc/pacman.d/cachyos-v4-mirrorlist [cachyos-core-znver4] Include = /etc/pacman.d/cachyos-v4-mirrorlist [cachyos-extra-znver4] Include = /etc/pacman.d/cachyos-v4-mirrorlist [cachyos] Include = /etc/pacman.d/cachyos-mirrorlist ``` **Finalize Installation:** ```bash # Update package databases and system sudo pacman -Syu ``` 🎉 **Congratulations!** Your system is now optimized with CachyOS packages. ### Debug Packages Debug symbols are available through debuginfod. Configure it by creating: ```bash # Create debuginfod configuration sudo mkdir -p /etc/debuginfod echo "https://debuginfod.cachyos.org" | sudo tee /etc/debuginfod/cachyos.urls ``` ### Uninstalling CachyOS Repositories For complete removal instructions, see our [Uninstallation Guide](https://wiki.cachyos.org/features/optimized_repos/#uninstalling-cachyos-repositories). ## SCX Schedulers CachyOS supports the new sched-ext (SCX) framework for userspace schedulers. For setup and configuration, see our [sched-ext Tutorial](https://wiki.cachyos.org/configuration/sched-ext/). > [!WARNING] > SCX schedulers are **not compatible** with the `linux-cachyos-bmq` kernel variant. ## Other Distributions CachyOS kernels are available for other Linux distributions through community efforts: ### Gentoo Linux Community-maintained ebuilds for dynamic kernel building: ```bash # Add the CachyOS kernels overlay eselect repository add CachyOS-kernels git https://github.com/Szowisz/CachyOS-kernels emaint sync -r CachyOS-kernels ``` **Repository:** [Szowisz/CachyOS-kernels](https://github.com/Szowisz/CachyOS-kernels) ### Fedora Linux COPR repository with multiple kernel variants: - `linux-cachyos-bore` - `linux-cachyos-rt-bore` - `linux-cachyos-bore-lto` - `linux-cachyos-lts` **Maintainer:** [bieszczaders](https://copr.fedorainfracloud.org/coprs/bieszczaders/kernel-cachyos/) **Installation:** Visit the [COPR page](https://copr.fedorainfracloud.org/coprs/bieszczaders/kernel-cachyos/) for setup instructions ### NixOS Precompiled kernels available through the xddxdd/nix-cachyos-kernel repository: **Repository:** [xddxdd/nix-cachyos-kernel](https://github.com/xddxdd/nix-cachyos-kernel) **Setup:** Follow the [installation guide](https://github.com/xddxdd/nix-cachyos-kernel#readme) ## Support & Community ### Get Help - **Discord:** [CachyOS Community](https://discord.gg/cachyos-862292009423470592) - **Forum:** [discuss.cachyos.org](https://discuss.cachyos.org) - **Telegram:** [CachyOS Group](https://t.me/+zCzPX4cAFjk1MTYy) ### Support Development Help us maintain repositories and build infrastructure: - **Patreon:** [patreon.com/CachyOS](https://www.patreon.com/CachyOS) - **BTC:** `bc1qmwglfchlc335du6pcu6w64cexu7cck0mzhyw42` - **ETH:** `0xc2dc77327F78A7B85Db3941Eb49e74F41E961649` - **LTC:** `LgGTwcEBcXqMgNT6XyyNWABMb7dZVtVg9w` ## Contributors Special thanks to our key contributors: - **[firelzrd](https://github.com/firelzrd/bore-scheduler)** - BORE Scheduler developer - **[Arch Linux](https://archlinux.org)** - Foundation distribution - **[Linux Kernel Community](https://github.com/torvalds/linux)** - Upstream kernel development - **All CachyOS contributors and community members**