Copyright (c) 2022, 2023 Gé Koerkamp / [email protected]

This script is used for building the necessary x86 platform files, which includes kernel, firmware, scripts etc. It does NOT build an image.
This is default set to kernel 6.1.y, but can still be used to build platform files with kernel 5.10.y
See the config.x86 in the config directory.

This build process has been tested on Debia Buster (Debian 10)and Ubuntu 22.04
You will need the following minimal packages:

build-essential bc kmod flex cpio libncurses5-dev libelf-dev libssl-dev bison rsync libncurses-dev debhelper

See at the end of this document.

git clone https://github.com/gkkpch/build-x86-platform --depth 1

cd build-x86-platform
./buildx86kernel.sh

After cloning/ updating the kernel and platform repos and applying volumio patches, the build process comes to a break-point and displays:

[ .. ] Now ready for additional sources and patches [ Info ]

At this point further patches can be made in the kernel tree.
Kernel patches are accumulated in ./patches/<major-kernelversion>/0001-custom-volumio.patch.
When you're ready, or did not have any patches, press [Enter]

Currently, custom files are not automatically saved, you need to copy these into the build repo's sources folder: ./sources/<major-kernelversion>/.
This needs to have same file structure as the corresponding kernel tree.
For an example, see ./sources/6.1.y.

There is also an opportunity to change kernel configuration settings, using the menuconfig dialogue which will appear.
Just exit when you have no changes.
Configuration modifications will be saved in /platform-x86/packages-buster/amd64-volumio-min..._defconfig and reused with future kernel compiles.

Release Candidate kernels are not part of the linux-stable repo.
The compilation of such a kernel requires

• manually clone the current kernel repo after checking the current rc name (e.g. 6.3-rc7):

git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git linux-6.3-rc7

• modification of ./config/x86.conf

  • comment the current kernel branch

  #KERNELBRANCH="6.1.y"
  

  • add a new one, e.g.

  KERNELBRANCH="6.3-rc7"
  

Next you need to create a kernel configuration file for the -rc kernel. Copy the last known amd64-volumio-min..._defconfig and name it (as an example) amd64-volumio_min_6.3-rc7_defconfig.

For the sources and patches, follow the instructions below (support for a new kernel).

Important Omit any custom sources or patches in case it is used for bugzilla reporting.

It is advised to use LTS kernels whenever possible. Once Volumio is working with an LTS version, you will have years of support to come. This kernel build process will keep maintenance effort to a minimum.

• Create the new ./sources/<kernelbranch> folder.

• Create the new ./patches/<kernelbranch> folder.

• Copy the custom sources from a previous ./sources/<major-kernelversion/ (the closest version you have) to the new patches folder.

  • Note: Some of the existing patches for Wireless Drivers may not apply anymore. Kernels 6.2.y and 6.3-rc7 already include more Realtek chip support. As an example, RTL8822BU is supported out-of-the-box (and a few more). Please check for duplicates by comparing the Kconfig files in Realtek folders like rtw88 and rtw99. Just copy the remaining custom patches.

• modify ./config/x86.conf

  • comment the current kernel branch

  #KERNELBRANCH="6.1.y"
  

  • add a new one, e.g.

  KERNELBRANCH="6.2.y"
  

• Start the build process.

Be aware, that patching or compiling may not work.

• in case patches do not apply
  • the build process will have stopped at

  Now ready for additional sources and patches
  Press [Enter] key to resume ...
  

  • fix the failed patch manually (it can be mismatched a few lines in case the source was changed in the new kernel version)
• in case the kernel does not apply because of errors in custom sources
  Consult the internet and apply the necessary fixes, this is not always trivial
  With the wireless drivers, refer to the README.md file in the corresponding ./sources folder.
  The repo owners may already have created patches.

There are two situations

• you wish to add a particular new or missing firmware binary and leave the rest as is
• you wish to add a complete new linux-firmware from kernel.org

Try to find out what is needed and then clone repo git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git

cd firmware
git clone git://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git new-fw

This will give you the latest stable firmware repo in directory new-fw.

Unpack the current linux-firmware tarball in firmware (on 20230104 this was firmware-20231216).

cd firmware
tar xfJ linux-fw-20221216.tar.xz

This gives you the current firmware tree in lib.

Locate the new firmware and place it at the exact same location in the current tree. Example:

cd firmware
cp new-fw/rtlwifi/rtl8188efw.bin lib/firmware/rtlwifi

Create a new linux-firmware tarball, note the name and the different date. Only overwrite an existing one when you add something which was missing.

cd firmware
tar cfJ linux-fw-20230104.tar.xz ./lib

Remove the temp folders

rm -r new-fw
rm -r lib

In case you added new firmware (not missing stuff), open config/config.x86 and add the date of the new firmware tarball (in this case "20230104") to the list of firmware releases.

LINUX_FW_REL=("20211027" "20221216" "20230104")

in both cases, start the merge script in the build-x86-platform root folder

./mergefirmware.sh

The new tarball will be copied to platform-x86

This is a little trickier and more time-consuming. The firmware from kernel.org is too big to use as-is, it needs cutting out the unnecessary firmware. The best way to do this is to clone the firmware repo as shown above, but do this in a directory outside the build-x86-platform.

Now comes to tedious part. Compare the contents of the current firmware tarball in firmware. On 20230104 this was linux-fw-20221216 and start with removing all directories in the new firmware repo which are not in the current one, unless you are sure it is a new one that matters (graphics, wifi). Do the same for the files in the root folder of the new firmware repo, keep the matching ones but also new binaries starting with "ar", "ath", "iwlwifi", "mt", "rt". When unsure, keep it.

Then bring this new folder in a "lib/firmware" structure (like the current one) and pack it to a tarball linux-fw-.tar.xz, where date is kernel.org's release date (should be visible when doing a git tag -l (it is the last one).

Add the new date to config/config.x86 and start the merge (see above)