Building Linux kernel on the Debian OS (Debian 10 Buster)

~ smansoft

Building Linux kernel on the Debian OS (Debian 10 Buster).

This blog-post describes simple method of the Linux Kernel building on Operational System Linux Debian 10.

At the current moment (when this blog-post is being created) (2021-06), last current version was Debian 10.10.

Current version of the Linux Kernel was 4.19.0-13 (4.19.160).

Follow kernels have been built, using this method:

  • Linux Kernel 4.19.194 (release: 2021-06-10)
  • Linux Kernel 5.11.22 (release: 2021-05-19)
  • Linux Kernel 5.12.10 (release: 2021-06-10)

Necessary version of the Linux Kernel could be found here:

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There are files .sign, distributed by www.kernel.org, which contain Digital Signature of correspondent files. Digital Signature of correspondent files can be verified, using methods, described here: Signatures. The verification allows to check if downloaded files correspondent original release versions and haven’t been changed.

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Building the Linux Kernel on the Linux Debian 10 OS:

  • If current user is root, all next commands (including copy to /usr/src, dpkg -i, update-grub2, … ) can be executed without any additional changes of permissions. In another case, it’s necessary to care about permissions and add sudo before some commands.
  • Download necessary version of the Linux Kernel.
  • Copy kernel archive to the directory: /usr/src.
  • Unpack archive:
    • if extension of the archive is .tar.gz:
      1. tar -zxf ./[Linux Kernel Sources].tar.gz
      2. For example: tar -zxf ./linux-5.12.10.tar.gz
    • if extension of the archive is .tar.xz:
      1. tar -Jxf ./[Linux Kernel Sources].tar.xz
      2. For example: tar -Jxf ./linux-5.12.10.tar.xz

Directory ./linux-5.12.10 will be created, that contains sources of the Linux Kernel (version 5.12.10).

  • Unpacked directory can be renamed from ./linux-5.12.10 to ./linux-source-5.12.10-amd64 , where ‘amd64‘ – target build platform:
    • mv ./linux-5.12.10 ./linux-source-5.12.10-amd64.

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  • Some software needs to be installed:
    • apt-get install gcc make git exuberant-ctags bc libssl-dev libelf-dev elfutils fakeroot build-essential zlib1g-dev libncurses5-dev.
  • Run follow command:
    • cd /boot.

This directory (/boot) contains installed Linux kernels and suite of config files, which have been used during building installed kernels. For example:

  • Linux Kernel 4.19.0-13 (4.19.160) :
    •  /boot/vmlinuz-4.19.0-13-amd64
  • Config of the Linux Kernel 4.19.0-13 (4.19.160) :
    • /boot/config-4.19.0-13-amd64.
  • Copy this file: /boot/config-4.19.0-13-amd64 to unpacked directory  (sources): /usr/src/linux-source-5.12.10-amd64.
  • Make one more copy of the file: /usr/src/linux-source-5.12.10-amd64.
    • For example:
      cd /usr/src/linux-source-5.12.10-amd64
      cp ./config-4.19.0-13-amd64 ./.config.

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  • Run
    • cd /usr/src/linux-source-5.12.10-amd64
  • and one of the following commands:
    • make config – text mode (questions)
    • make menuconfig – text mode (menu)
    • make xconfig – graphical mode (menu)

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  • All menu options can be configured, but it’s necessary to save current configuration to file:
    /usr/src/linux-source-5.12.10-amd64/.config.

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  • Script saves default values of all non-configured menu options.
    • I.e. the most quick way of configuring:
    • just:
      • make menuconfig
    • and save configuration to the file
      • ./.config.

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  • Then open file:
    /usr/src/linux-source-5.12.10-amd64/Makefile
    and setup value: EXTRAVERSION.

    • For example:
      • EXTRAVERSION = -amd64

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  • Follow commands can be used for cleaning and build:
    • make clean – cleaning built binaries and temporary files
      or
    • make deb-pkg – full build and binary images creating.
  • After finishing the build follow files will be created in the current directory
    /usr/src/linux-source-5.12.10-amd64/ :

linux-5.12.10-amd64_5.12.10-amd64-1.dsc
linux-5.12.10-amd64_5.12.10-amd64-1_amd64.buildinfo
linux-5.12.10-amd64_5.12.10-amd64-1_amd64.changes
linux-5.12.10-amd64_5.12.10-amd64.orig.tar.gz
linux-5.12.10-amd64_5.12.10-amd64-1.diff.gz

linux-headers-5.12.10-amd64_5.12.10-amd64-1_amd64.deb
linux-image-5.12.10-amd64_5.12.10-amd64-1_amd64.deb
linux-image-5.12.10-amd64-dbg_5.12.10-amd64-1_amd64.deb
linux-libc-dev_5.12.10-amd64-1_amd64.deb

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  • For installing built .deb modules, use follow commands:
    • cd /usr/src/linux-source-5.12.10-amd64
    • dpkg -i ./linux-*.deb
  • After that, new kernel will be installed to the directories:
    • /boot
    • /usr/lib/modules/5.12.10-amd64
    • /usr/lib/debug/lib/modules/5.12.10-amd64
    • /usr/src

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  • If grab2 is installed as boot loader package, follow command should be executed:
    • update-grub2
  • that provides configuring the file:
    • /boot/grub/grub.cfg

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This execution (update-grub2) is optional, as during running “dpkg -i ./linux-*.deb“, updating the /boot/grub/grub.cfg is provided by default.

  • After reboot, new version of the kernel will be loaded:
    • file: /proc/version

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Published by smansoft