5dd0c6e3c0
By using the kernel "nolibc" header to avoid requiring a C library, we can bring the initramfs size to around 4k This does involve a tiny bit of inline mips assembly which I'm not sure about. gcc seems unwilling to generate the code to load $gp at function entry of main(), so we do it by hand - but I'd rather find out why gcc doesn't.
42 lines
1 KiB
Nix
42 lines
1 KiB
Nix
{
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config
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, pkgs
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, lib
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, ...
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}:
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let
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inherit (lib) mkEnableOption mkIf;
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inherit (pkgs) runCommand callPackage writeText;
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in
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{
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options = {
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boot.initramfs = {
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enable = mkEnableOption "enable initramfs";
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default = false;
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};
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};
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config = mkIf config.boot.initramfs.enable {
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kernel.config = {
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BLK_DEV_INITRD = "y";
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INITRAMFS_SOURCE = builtins.toJSON "${config.outputs.initramfs}";
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# INITRAMFS_COMPRESSION_LZO = "y";
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};
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outputs = {
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initramfs =
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let inherit (pkgs.pkgsBuildBuild) gen_init_cpio;
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in runCommand "initramfs.cpio" {} ''
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cat << SPECIALS | ${gen_init_cpio}/bin/gen_init_cpio /dev/stdin > $out
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dir /proc 0755 0 0
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dir /dev 0755 0 0
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nod /dev/console 0600 0 0 c 5 1
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nod /dev/mtdblock0 0600 0 0 b 31 0
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dir /target 0755 0 0
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dir /target/persist 0755 0 0
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dir /target/nix 0755 0 0
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file /init ${pkgs.preinit}/bin/preinit 0755 0 0
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SPECIALS
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'';
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};
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};
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}
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