How to build custom Pop!_OS kernel? (with patch)

[bluetiger9]

Hi! 🙂

I would like to build and install a custom kernel version with a patch, based on the current Pop!_OS 6.6.10-76060610-generic kernel. Are there any up to date instructions on how to build and install a custom Pop!_OS kernel?

The kernel patch is a simple quirk, that should fix a microphone issue in a Lenovo laptop, similar to the 171726a commit.

A guide I trying to follow is:
https://tutorialforlinux.com/2021/01/04/step-by-step-build-kernel-pop_os-guide/

Steps:

• clone Pop_OS! Linux kernel repository

$ git clone --depth 1 https://github.com/pop-os/linux.git; cd linux

• use the current kernel config

$ sudo cat /boot/config-6.6.10-76060610-generic > .config

• clean and build with deb-pkg

$ make clean
$ make deb-pkg LOCALVERSION=-custom KDEB_PKGVERSION=$(make kernelversion)-1

This last command first gives a warning about uncommitted changes, and fails with a patch related error (see bellow).

Can somebody help me with this?

Log:

➜  linux git:(master) make deb-pkg LOCALVERSION=-custom KDEB_PKGVERSION=$(make kernelversion)-1                        [10/02 | 1:36:33]

  SYNC    include/config/auto.conf.cmd
  HOSTCC  scripts/basic/fixdep
  HOSTCC  scripts/kconfig/conf.o
  HOSTCC  scripts/kconfig/confdata.o
  HOSTCC  scripts/kconfig/expr.o
  LEX     scripts/kconfig/lexer.lex.c
  YACC    scripts/kconfig/parser.tab.[ch]
  HOSTCC  scripts/kconfig/lexer.lex.o
  HOSTCC  scripts/kconfig/menu.o
  HOSTCC  scripts/kconfig/parser.tab.o
  HOSTCC  scripts/kconfig/preprocess.o
  HOSTCC  scripts/kconfig/symbol.o
  HOSTCC  scripts/kconfig/util.o
  HOSTLD  scripts/kconfig/conf
  UPD     include/config/kernel.release
  GEN     debian
============================ WARNING ============================
Your working tree has diff from HEAD, and also untracked file(s).
Please make sure you did 'git add' for all new files you need in
the source package.
=================================================================
  UPD     .tmp_HEAD
  ARCHIVE linux.tar.gz
dpkg-buildpackage --build=source,binary --no-pre-clean --unsigned-changes --unsigned-source --compression=gzip --rules-file='make -f debian/rules' --jobs=1 -r'fakeroot -u' -a$(cat debian/arch)
dpkg-buildpackage: info: source package linux-upstream
dpkg-buildpackage: info: source version 6.6.10-1
dpkg-buildpackage: info: source distribution jammy
dpkg-buildpackage: info: source changed by bluetiger <bluetiger@Attila-Laptop>
dpkg-buildpackage: info: host architecture amd64
 dpkg-source --compression=gzip --before-build .
dpkg-source: info: using options from linux/debian/source/local-options: --diff-ignore --extend-diff-ignore=.*
dpkg-buildpackage: warning: building a source package without cleaning up as you asked; it might contain undesired files
 dpkg-source --compression=gzip -b .
dpkg-source: info: using options from linux/debian/source/local-options: --diff-ignore --extend-diff-ignore=.*
dpkg-source: info: using source format '3.0 (quilt)'
dpkg-source: info: building linux-upstream using existing ./linux-upstream_6.6.10.orig.tar.gz
dpkg-source: info: using patch list from debian/patches/series
The next patch would delete the file debian/canonical-certs.pem,
which does not exist!  Skipping patch.
1 out of 1 hunk ignored

....

The next patch would delete the file debian/zfs-modules.ignore,
which does not exist!  Skipping patch.
1 out of 1 hunk ignored
dpkg-source: info: the patch has fuzz which is not allowed, or is malformed
dpkg-source: info: if patch 'diff.patch' is correctly applied by quilt, use 'quilt refresh' to update it
dpkg-source: info: if the file is present in the unpacked source, make sure it is also present in the orig tarball
dpkg-source: error: LC_ALL=C patch -t -F 0 -N -p1 -u -V never -E -b -B .pc/diff.patch/ --reject-file=- < linux.orig.4EjSEs/debian/patches/diff.patch subprocess returned exit status 1
dpkg-buildpackage: error: dpkg-source --compression=gzip -b . subprocess returned exit status 2
make[2]: *** [scripts/Makefile.package:146: deb-pkg] Error 2
make[1]: *** [/home/bluetiger/kernel/linux/Makefile:1544: deb-pkg] Error 2
make: *** [Makefile:234: __sub-make] Error 2

[bluetiger9]

Figured this out! 🙂 Instead of make deb-pkg ..., looks like we should use make bindeb-pkg .... This fixes the patch errors mentioned above.

So, to build and install a Pop!_OS Linux kernel with a patch:

1. Clone Pop_OS! Linux kernel repository

$ git clone --depth 1 https://github.com/pop-os/linux.git; cd linux

2. Use the current kernel config

$ cp /boot/$(uname -r) > .config

• and change the following settings in .config
  • remove trusted and revocation keys:

    CONFIG_SYSTEM_TRUSTED_KEYS=""
    CONFIG_SYSTEM_REVOCATION_KEYS=""
    

  • disable kernel module compression:
    (fixes random SSL signing error, ref. https://askubuntu.com/a/1497413)

    CONFIG_MODULE_COMPRESS_NONE=y
    # CONFIG_MODULE_COMPRESS_ZSTD is not set
    

3. Apply any source code changes and patches

4. Clean and build with bindeb-pkg

$ make clean
$ make -j12 bindeb-pkg LOCALVERSION=-custom KDEB_PKGVERSION=$(make kernelversion)-1

6. Install the new kernel

$ cd ..
$ sudo dpkg -i linux-headers-6.6.10-custom_6.6.10-1_amd64.deb linux-image-6.6.10-custom_6.6.10-1_amd64.deb

and set it as the default with kernelstub:

sudo kernelstub -v -k /boot/vmlinuz-6.6.10-custom -i /boot/initrd.img-6.6.10-custom

7. Reboot