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Linux kernel: Difference between revisions

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→Custom configuration: emphasise structuredExtraConfig and note what actually causes the "unused option" errors
DHCP (talk | contribs)
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m prefix shell comments with $ to get "comment" highlighting instead of "root shell"
 
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</syntaxHighlight>
</syntaxHighlight>
<syntaxhighlight lang="nix">
<syntaxhighlight lang="nix">
nix-repl> :l <nixpkgs>
nix-repl> pkgs = import <nixpkgs> {}
Added 12607 variables.
Added 12607 variables.


nix-repl> pkgs.linuxPackages
nix-repl> pkgs.linuxKernel.packages
pkgs.linuxPackages                          pkgs.linuxPackages_custom
pkgs.linuxPackages                          pkgs.linuxPackages_custom
pkgs.linuxPackages-libre                    pkgs.linuxPackages_custom_tinyconfig_kernel
pkgs.linuxPackages-libre                    pkgs.linuxPackages_custom_tinyconfig_kernel
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     name = "crashdump-config";
     name = "crashdump-config";
     patch = null;
     patch = null;
     structuredExtraConfig = {
     structuredExtraConfig = with lib.kernel; {
       CRASH_DUMP = lib.kernel.yes;
       CRASH_DUMP = yes;
       DEBUG_INFO = lib.kernel.yes;
       DEBUG_INFO = yes;
       PROC_VMCORE = lib.kernel.yes;
       PROC_VMCORE = yes;
       LOCKUP_DETECTOR = lib.kernel.yes;
       LOCKUP_DETECTOR = yes;
       HARDLOCKUP_DETECTOR = lib.kernel.yes;
       HARDLOCKUP_DETECTOR = yes;
     };
     };
   } ];
   } ];
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</syntaxhighlight>
</syntaxhighlight>


Alternatively, you can pass a string as <code>extraConfig</code>, with option names and answers formatted like so:
Another way is to create an overlay to configure {{ic|structuredExtraConfig}}. This allows for more flexibility, since you can basically override any available kernel option<ref>[https://github.com/NixOS/nixpkgs/blob/e6db435973160591fe7348876a5567c729495175/pkgs/os-specific/linux/kernel/generic.nix#L11-L56<tt>pkgs/os-specific/linux/kernel/generic.nix#L11-L56</tt>]</ref>.
 
<pre>
CRASH_DUMP y
DEBUG_INFO y
PROC_VMCORE y
LOCKUP_DETECTOR y
HARDLOCKUP_DETECTOR y
</pre>
 
Another way is to create an overlay to configure either {{ic|extraConfig}} or {{ic|structuredExtraConfig}}. This allows for more flexibility, since you can basically override any available kernel option<ref>[https://github.com/NixOS/nixpkgs/blob/e6db435973160591fe7348876a5567c729495175/pkgs/os-specific/linux/kernel/generic.nix#L11-L56<tt>pkgs/os-specific/linux/kernel/generic.nix#L11-L56</tt>]</ref>. Using {{ic|structuredExtraConfig}} is recommended as it checks if the configured option are correct.


{{file|/etc/nixos/configuration.nix|nix|<nowiki>
{{file|/etc/nixos/configuration.nix|nix|<nowiki>
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}
}
</nowiki>}}
</nowiki>}}
Note that pinning the kernel version will likely require manual recompilation, which may be slow on older hardware. See [https://discourse.nixos.org/t/pin-kernel-version/50630/3 this thread] for a related discussion.


=== Debugging a failed configuration  ===
=== Debugging a failed configuration  ===
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Please provide a comparison with other distributions' kernel:
Please provide a comparison with other distributions' kernel:
- arch: https://github.com/archlinux/svntogit-packages/blob/packages/linux/trunk/config
 
- debian: https://salsa.debian.org/kernel-team/linux/blob/master/debian/config/config and the ARCH specific ones
* Arch: https://gitlab.archlinux.org/archlinux/packaging/packages/linux/-/blob/main/config
* Debian: https://salsa.debian.org/kernel-team/linux/blob/master/debian/config/config and the ARCH specific ones


== Booting a kernel from a custom source ==
== Booting a kernel from a custom source ==
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           kernelPatches = [];
           kernelPatches = [];


           extraConfig = ''
           structuredExtraConfig = with lib.kernel; {
             INTEL_SGX y
             INTEL_SGX = yes;
           '';
           };


           extraMeta.branch = "5.4";
           extraMeta.branch = "5.4";
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     owner = "aramg";
     owner = "aramg";
     repo = "droidcam";
     repo = "droidcam";
     rev = "v${version}";
     tag = "v${version}";
     hash = "1d9qpnmqa3pfwsrpjnxdz76ipk4w37bbxyrazchh4vslnfc886fx";
     hash = "1d9qpnmqa3pfwsrpjnxdz76ipk4w37bbxyrazchh4vslnfc886fx";
   };
   };
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<syntaxHighlight lang=console>
<syntaxHighlight lang=console>
$ nix-shell
$ nix-shell
# to configure
$ # to configure
$ nix-shell> make $makeFlags defconfig -j $(nproc)
$ nix-shell> make $makeFlags defconfig -j $(nproc)
# to build
$ # to build
$ nix-shell> make $makeFlags -j $(nproc)
$ nix-shell> make $makeFlags -j $(nproc)
</syntaxHighlight>
</syntaxHighlight>
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<syntaxHighlight lang=console>
<syntaxHighlight lang=console>
$ nix-shell
$ nix-shell
# to configure
$ # to configure
$ nix-shell> make $makeFlags defconfig -j $(nproc)
$ nix-shell> make $makeFlags defconfig -j $(nproc)
# to build
$ # to build
$ nix-shell> make $makeFlags -j $(nproc)
$ nix-shell> make $makeFlags -j $(nproc)
</syntaxHighlight>
</syntaxHighlight>
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=== Overriding kernel packages ===
=== Overriding kernel packages ===


In order to override <code>linuxPackages</code>, use the <code>extend</code> attribute. Example:
In order to override <code>linuxPackages</code>, an alias of <code>linuxKernel.packages</code>, use the <code>extend</code> attribute. Example:


<syntaxHighlight lang=nix>
<syntaxHighlight lang=nix>
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     })
     })
   ];
   ];
</syntaxHighlight>
You can also use <code>kernelPackagesExtensions</code> in a similar fashion to override <code>linuxKernel.packages</code>:
<syntaxHighlight lang=nix>
nixpkgs.overlays = [ 
  (_: prev: {
    kernelPackagesExtensions = prev.kernelPackagesExtensions ++ [
      (_: linuxPrev: {
        digimend = linuxPrev.digimend.overrideAttrs (prevAttrs: {
          postPatch = prevAttrs.postPatch or "" + ''
            substituteInPlace "hid-uclogic-core.c" \
              --replace-fail "del_timer_sync" "timer_shutdown_sync"
          '';
        });
      })
    ];
  })
];
</syntaxHighlight>
</syntaxHighlight>


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}
}
</syntaxhighlight>
</syntaxhighlight>
== Troubleshooting ==
=== Build fails ===
==== Too high ram usage ====
turn off <code>DEBUG_INFO_BTF</code>


== See also ==
== See also ==
Retrieved from "https://wiki.nixos.org/wiki/Linux_kernel"