User:Anthumchris:How to build the Alpine Linux kernel: Difference between revisions

Latest revision as of 22:57, 3 December 2024

How to build the Alpine Linux kernel

This Howto quickly demonstrates building/compiling the default Alpine Linux kernels. Kernel customizations (not covered here) allow you to experiment by adding/removing kernel modules/features. For example, Alpine releases multiple kernels that vary in features and file sizes. Alpine kernels extend the standard Linux kernel and build within a few minutes to a few hours (depending on the speed of your system) using abuild, aports, and alpine-sdk.

Before you start

A running instance of Alpine Linux and a non-root user with doas privileges (i.e. sudo, wheel group) are required to use abuild.

Build & install the kernel

Build

doas apk add alpine-sdk
doas addgroup USERNAME abuild         # your non-root user

git clone --depth 1 https://gitlab.alpinelinux.org/alpine/aports.git
abuild-keygen --append --install
doas chmod a+r /etc/apk/keys/*        # ensure new keys are readable

cd aports/main/linux-lts/
time abuild -crK

Identify backup

Identify the package name of your current kernel (e.g. linux-lts, linux-virt). This example shows that linux-lts is the current package that we would revert to as a backup.

echo "kernel: $(uname -r)"
apk list --installed linux-*

Install

Find the newly-built kernel file to install. This example shows how to install a newly-built x86_64 LTS kernel:

ls -r ~/packages/main/*
doas apk add FILENAME
doas reboot

After rebooting, verify the newly-installed kernel version:

echo "kernel: $(uname -r)"

Revert

If needed, revert to the previous backup kernel package we identified earlier. This example shows how to revert to the previous "alpine-lts" package after removing the newly-installed "alpine-lts" (both are named "alpine-lts" yet refer to different versions/locations):

apk list linux-lts            # newly-compiled kernel installed
doas apk del linux-lts        # newly-compiled kernel from file
doas apk add linux-lts        # previous kernel from Alpine repo
apk list linux-lts            # previous kernel installed
doas reboot

@@ Line 1: / Line 1: @@
-== How build the Alpine Linux kernel ==
+== How to build the Alpine Linux kernel ==
-A customized build of the Alpine Linux kernel may be needed if you are experimenting with adding/removing kernel features and modules. The Alpine kernel extends the standard [https://www.kernel.org/linux.html Linux kernel] and builds within a few minutes to a few hours (depending on the speed of your system) using <code>[[abuild]]</code> and [https://gitlab.alpinelinux.org/alpine/aports aports].
+This [[Tutorials and Howtos|Howto]] quickly demonstrates building/compiling the default Alpine Linux [[Kernels|kernels]]. Kernel customizations (not covered here) allow you to experiment by adding/removing kernel modules/features. For example, Alpine releases multiple [[Kernels|kernels]] that vary in features and file sizes.  Alpine kernels extend the standard [https://www.kernel.org/linux.html Linux kernel] and build within a few minutes to a few hours (depending on the speed of your system) using <code>[[abuild]]</code>, [https://gitlab.alpinelinux.org/alpine/aports aports], and [https://pkgs.alpinelinux.org/package/edge/main/x86_64/alpine-sdk alpine-sdk].
 == Before you start ==
-A running instance of Alpine Linux and a non-root user are required to use <code>[[abuild]]</code>.
+A running instance of Alpine Linux and a non-root user with [https://pkgs.alpinelinux.org/package/edge/main/x86_64/doas doas] privileges (i.e. sudo, wheel group) are required to use <code>[[abuild]]</code>.
 == Build & install the kernel ==
 === Build ===
-Run as root:
 <pre>
-apk add alpine-sdk           # install required packages
+doas apk add alpine-sdk
-addgroup USERNAME abuild     # your non-root user
+doas addgroup USERNAME abuild         # your non-root user
-</pre>
-Run as non-root user:
-<pre>
 git clone --depth 1 https://gitlab.alpinelinux.org/alpine/aports.git
-abuild-keygen --append
+abuild-keygen --append --install
+doas chmod a+r /etc/apk/keys/*        # ensure new keys are readable
-# build/install the kernel
 cd aports/main/linux-lts/
 time abuild -crK
 </pre>
+=== Identify backup ===
+Identify the package name of your current kernel (e.g. linux-lts, linux-virt). This example shows that '''linux-lts''' is the current package that we would revert to as a backup.
+<pre>
+echo "kernel: $(uname -r)"
+apk list --installed linux-*
+</pre>
+[[File:Alpine-kernel-package2.png|600px]]
 === Install ===
+Find the newly-built kernel file to install. This example shows how to install a newly-built x86_64 LTS kernel:
 <pre>
-apk add /home/USERNAME/packages/.....................................
+ls -r ~/packages/main/*
+doas apk add FILENAME
+doas reboot
 </pre>
+[[File:Alpine-kernel-install.png|600px]]
+After rebooting, verify the newly-installed kernel version:
+<pre>
+echo "kernel: $(uname -r)"
+</pre>
+[[File:Alpine-kernel-new.png|320px]]
+=== Revert ===
+If needed, revert to the previous backup kernel package we identified earlier. This example shows how to revert to the previous "alpine-lts" package after removing the newly-installed "alpine-lts" (both are named "alpine-lts" yet refer to different versions/locations):
+<pre>
+apk list linux-lts            # newly-compiled kernel installed
+doas apk del linux-lts        # newly-compiled kernel from file
+doas apk add linux-lts        # previous kernel from Alpine repo
+apk list linux-lts            # previous kernel installed
+doas reboot
+</pre>
+[[File:Alpine-kernel-revert.png|465px]]
 == See Also ==
 * [[Kernels]]
-* [[Custom Kernel]]
+* [[Custom Kernel|Custom Kernel (2018-present)]]