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Look at this Makefile — then look at this NixOS package derivation. Appears simple but I couldn’t for the life of me divine how to quickly compile a custom/patched kernel module on NixOS. Abstractions… are very magical. The guide is cool and all, but it’s a better time investment to guesstimate the relationship between the higher/lower layer. This friendly example looks more like this in reality though ;-)

#linux

A NixOS configuration for a working sound driver on an A1418 Cirrus Logic CS8409/CS42L83.

  
  
    nix
  
  
  { stdenv, lib, fetchgit, linuxKernel, kernel ? linuxKernel.kernels.linux_5_15
, version ? "d0d785dc1859b09299bde6d0f1d6786a0d610e7f" }:

stdenv.mkDerivation {

  inherit version;
  name = "sna-hda-codec-cs8409-${version}-module-${kernel.modDirVersion}";

  # Upstream: https://github.com/davidjo/snd_hda_macbookpro

  src = fetchgit {
    url = "https://github.com/egorenar/snd-hda-codec-cs8409.git";
    rev = version;
    sha256 = "sha256-0UeoERcYpM+ojeZ7dDIE3ruTIoHkkC+s7FcoEVUTR0w=";
  };

  hardeningDisable = [ "pic" ];
  nativeBuildInputs = kernel.moduleBuildDependencies;

  NIX_CFLAGS_COMPILE = [ "-g" "-Wall" "-Wno-unused-variable" "-Wno-unused-function" ];

  makeFlags = kernel.makeFlags ++ [
    "INSTALL_MOD_PATH=$(out)"
    "KERNELRELEASE=${kernel.modDirVersion}"
    "KERNEL_DIR=${kernel.dev}/lib/modules/${kernel.modDirVersion}/build"
  ];

  postPatch = ''
    printf '
    snd-hda-codec-cs8409-objs := patch_cs8409.o patch_cs8409-tables.o
    obj-$(CONFIG_SND_HDA_CODEC_CS8409) += snd-hda-codec-cs8409.o

    KBUILD_EXTRA_CFLAGS = "-DAPPLE_PINSENSE_FIXUP -DAPPLE_CODECS -DCONFIG_SND_HDA_RECONFIG=1"

    KERNELRELEASE ?= $(shell uname -r)
    KERNEL_DIR    ?= /lib/modules/$(KERNELRELEASE)/build
    PWD           := $(shell pwd)

    default:
    	make -C $(KERNEL_DIR) M=$(PWD) CFLAGS_MODULE=$(KBUILD_EXTRA_CFLAGS)

    install:
    	make -C $(KERNEL_DIR) M=$(PWD) modules_install
    ' \
    > Makefile

    sed --in-place 's|<sound/cs42l42.h>|"${linuxKernel.kernels.linux_6_0.dev}/lib/modules/${linuxKernel.kernels.linux_6_0.modDirVersion}/source/include/sound/cs42l42.h"|'  patch_cs8409.h
    sed --in-place 's|hda_local.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_local.h|'                                                      patch_cs8409.h
    sed --in-place 's|hda_jack.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_jack.h|'                                                        patch_cs8409.h
    sed --in-place 's|hda_generic.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_generic.h|'                                                  patch_cs8409.h
    sed --in-place 's|hda_auto_parser.h|${kernel.dev}/lib/modules/${kernel.modDirVersion}/source/sound/pci/hda/hda_auto_parser.h|'                                          patch_cs8409.h
  '';

  meta = { platforms = lib.platforms.linux; };
}

Then build it as a extra/custom kernel module. The results of stumbling upon yet another troublesome device…

  
  
    nix
  
  
  { pkgs, ... }:

{
  boot = {
    extraModulePackages = [
      (pkgs.callPackage ../packages/snd-hda-cs8409/default.nix {
        kernel = pkgs.linux_5_15;
      })
    ];
  };
}

#gists #linux

Kangaroo mother and baby (© Belle Ciezak/Shutterstock)

#feeds

Version controlling (also called revision control or source control) your database data is pretty easy as long as you don’t have any binary content stored in the database, you just commit your SQL dump to the version control software, it’s just SQL …

#feeds