Building Slackware AArch64 Linux Kernel packages from the Raspberry Pi Kernel fork

The Slackware ARM build system was built to abstract the common functionality of the build scripts into a library and configuration file, enabling global changes to be made in a single location.

The Slackware ARM source tree works as an 'overlay' to the Slackware x86/64 upstream source tree. This way all assets (sources, patches, etc.) are referenced from the Slackware ARM build system, but are never duplicated. The Slackware ARM build scripts (called <packagename>.SlackBuild) are however customised to operate within the Slackware ARM build system, but produce identical packages to the x86 upstream versions. This approach enables architecture customisations to be easily made, whilst minimising effort required to synchronize source assets.

This document assumes that you're building on a full Slackware system, because the Slackware Linux Kernel package build process requires a number of development tools to be available.

This document provides some basic instructions using the slackpkg tool to ensure that your system has the latest versions of these packages available.

If you don't have slackpkg set up or would prefer to do this manually, you may use the upgradepkg –install-new tool instead.

This document covers working on Slackware -current (the development branch), but you can use the same steps for a stable release by switching the name of the tree - e.g. -current → -15.0.

Within your home directory, create a directory to contain the Slackware AArch64 source tree:

$ cd # return to the root of your home directory (not the 'root' user):
$ mkdir slackware ; cd slackware

Determine where you are in the file system, as you will need this shortly:

$ pwd
/home/mozes/slackware

$ rsync \
   --delete -Pavv \
   ftp.arm.slackware.com::slackwarearm/slackwareaarch64-current .

Before the Kernel can be built, you need to ensure that you have certain packages installed. This list isn't fully inclusive because you should build the Kernel on a full system, but particularly for Slackware -current, you need to ensure that you have the latest version of the Kernel packages installed so that it's aligned with the Slackware AArch64 source tree.

As root:

# slackpkg update

The Slackware ARM build system uses a package named slackkit that contains the library functions to build the packages. This package is installed by default, but if you don't have it :

As root, install/upgrade the package:

# slackpkg install slackkit

This list isn't exhaustive but should cover it (if more dependencies are required, please drop mozes@slackware.com a mail with them and I'll update this doc!)

# slackpkg install eudev mdadm lvm2 device-tree-compiler rsync

As root, you need to set up some symlinks to the location of your Slackware AArch64 source tree.

# cd # return to root's home directory
# ln -vfs /home/mozes/slackware/slackwareaarch64-current/slackware tgzstash
# ln -vfs /home/mozes/slackware/slackwareaarch64-current 

There is a script within the Slackware AArch64 Kernel source directory (slackwareaarch64-<version>/source/k) named build_altsrc_kernel.sh which will help build Slackware packages from alternate Kernel source repositories.

It uses a 'plugin' style system to store settings for specific repositories.

Elevate privileges to root:

$ su - 

Enter the directory in which the Slackware AArch64 source is stored. In this document, it's here:

# cd ~mozes/slackware/slackwareaarch64-current/source/k # the ~ expands to the user's home directory (/home in this case)

The default settings should be good for most users, but note that by default it will need about 3G bytes of space in /tmp. If you don't have enough space, you should run it with the relevant command line operator –tmpdir to change the location.

The script supports the –help command line parameter, which explains the available options.

# ./build_altsrc_kernel.sh --help

By default the tool is configured for the Raspberry Pi Kernel fork online git repository, as this is what this author uses to build the packages provided to bridge the gap between the feature and bug fix disparity between the official Linux Kernel and Raspberry Pi's.

The Raspberry Pi settings can be found in build_altsrc_kernel.conf/rpi.

For most users you'll want to use the default settings.

First, check what version of the Linux Kernel is available at the repository:

# ./build_altsrc_kernel.sh -D

# ./build_altsrc_kernel.sh -D

---------------------------
Temporary directory.........: /tmp/altkernelpkgs/
Kernel source directory.....: /tmp/altkernelpkgs//src
Package store directory.....: /tmp/altkernelpkgs//pkg

GIT repository..............: https://github.com/raspberrypi/linux.git
Kernel branch...............: rpi-6.1.y
Slackware package build tag : 1_rpi
Save Kernel headers package : No

Hardware Model helper script: /root/ac/source/k/build_altsrc_kernel.conf/default
---------------------------

Kernel version in web repository https://raw.githubusercontent.com/raspberrypi/linux/rpi-6.1.y: 6.1.31

Continuing as root, run the build script:

# ./build_altsrc_kernel.sh

After a few hours your Kernel will have been built, with the packages (by default) placed within /tmp/altkernelpkgs/pkg.

You should read the this guide before transitioning to them, as there are a few caveats due to the configuration disparity between the default RPi Kernel config and the generic Slackware Kernel configuration.