Xanmod-Kernel-Builder

An straightforward workflow for building the Xanmod kernel on your device.

This workflow facilitates the creation of a Xanmod kernel, incorporating multiple versions of Clang/LLVM with LLVM=1 and LLVM_IAS=1 specifically tailored for debian/ubuntu distros. (Can be adapted for Arch Linux with ease)

It utilizes the following script to set up LLVM: https://apt.llvm.org/llvm.sh

The kernel is built with Clang/LLVM 19, the latest version at the time of writing.

The configuration in the repository builds a kernel tailored to my laptop (DO NOT use it).

• build creates a non-generic kernel, utilizing the config in the repository.
• build_generic generates a generic kernel (building 4 versions) with Full LTO and CONFIG_PREEMPT=y, using config_general in the repository.

Kanged from: https://xanmod.org/ (xanmod website)

Notice

1. GitHub Actions service is NOT unlimited, so to prevent waste, use a stable and tested configuration locally first, then edit the config file in the repository.

2. Before making any changes, ensure that the repository belongs to you. "Fork" it if you intend to commit code; otherwise, use "Use this template".

shamelessly kanged instructions from here

To easily create a device-specfic config here is a noob-friendly guide

// if you dont want to make a config just use the generic builds //

Prerequisites:

> Basic command-line experience , like using `cd` , basic `bash` etc.

> Approximately 10-20 GB of free disk space, depending on your configuration.

1. Install the Xanmod kernel you want to build; for example, to build kernel 6.1 LTS, install the official Xanmod 6.1 build and boot into it.

2. Clone the Xanmod source:

git clone --depth=1 https://gitlab.com/xanmod/linux -b 6.1 kernel/xanmod  

the build puts the binaries in the kernel dir while the tree is in xanmod dir

3. Install Build Dependencies

For Ubuntu 22.04

sudo apt update
sudo apt upgrade
sudo apt install gcc clang llvm lld g++ build-essential bison flex pkg-config qtcreator qtbase5-dev qt5-qmake qttools5-dev-tools libssl-dev libncurses-dev libelf-dev elfutils lz4 debhelper dh-virtualenv zstd -y 

4. If you less than 16 gb ram then add some disk swap or zram , you can google it i have 12 gb of DDR4 , so i added some zram , which made the build process slightly faster

5. We are going to use make localyesconfig to make a stripped down config.

   It Create a config based on current config and loaded modules (lsmod). Disables any module option that is not needed for the loadedmodules. Make sure to connect all the usb devices and turn on bluetooth and be connected to internet then cd to kernel/xanmod and run

make distclean
rm -rf vmlinux-gdb.py
make localyesconfig

then

make CC=clang LD=ld.lld LLVM=1 LLVM_IAS=1 xconfig

or

make CC=clang LD=ld.lld LLVM=1 LLVM_IAS=1 menuconfig

both xconfig and menuconfig have gui , which can be used to edit the config genrated by make localyesconfig , you can enable some stuff here like lto , kvm support , weather to optmize for size or performance , cpu specfic optmizations etc and other stuff that you are going to use

NEVER enable CONFIG_MNATIVE_AMD or CONFIG_MNATIVE_INTEL because it optmizes for the processor the kernel was built on , rather specify your processor specfically because you are going to build on a workflow , if you are going to build locally and use the kernel on the same machine then enable them

lets say you have a intel skylake or kabylake processor

you can set CONFIG_MSKYLAKE=y and you can use xconfig and menuconfig for that , as they allow searching these configs and automatically adapt the config , now save your config and lets start the build:

make \
  CC=clang \
  LD=ld.lld \
  LLVM=1 \
  LLVM_IAS=1 \
  LOCALVERSION=-xanmod-clang \
  deb-pkg \
  -j$(nproc)

the deb-pkg neatly packs the kernel into .deb files which are very easy to install

Find the .deb files in the kernel directory, next to the xanmod directory. Install them using:

sudo dpkg -i *.deb

boot into the kernel and check it with uname -r it should be something like xxx-xanmod-clang-xxx

Test thoroughly, and if all goes well, edit the config file in the repository and paste the content from your .config file, located in the xanmod directory.

Tips

Make sure to enable Full LTO in your configs and if you have 4 gb ram or less then cosider enabling Thin LTO

You don't need to enable LTO in your local configs when building locally, as it increases build time. Just build without LTO and enable Full LTO in your config when committing the .config to the repo for all the benefits of LTO.

TL;DR

This is a straightforward workflow for building the Xanmod kernel with Clang/LLVM on Ubuntu/Debian. It uses the latest LLVM version (19 at the time of writing) and has options for building a non-generic kernel (build) or a generic kernel with Full LTO and CONFIG_PREEMPT=y (build_generic).

The document provides a beginner-friendly guide to create a device-specific kernel config:

1. Install Xanmod kernel you want to build.
2. Clone Xanmod source.
3. Install build dependencies.
4. Add swap/zram if <16GB RAM.
5. Use make localyesconfig to generate a config based on your system.
6. Customize the config via make xconfig or make menuconfig.
7. Build kernel with make CC=clang LD=ld.lld LLVM=1 LLVM_IAS=1 LOCALVERSION=-xanmod-clang deb-pkg -j$(nproc).
8. Install .deb packages.

Tips:

• Enable Full LTO in configs.
• Use Thin LTO if <4GB RAM.
• Build without LTO locally, enable Full LTO when committing config.