113 lines
5 KiB
Nix
113 lines
5 KiB
Nix
# Create an initramfs containing the closure of the specified
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# file system objects. An initramfs is used during the initial
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# stages of booting a Linux system. It is loaded by the boot loader
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# along with the kernel image. It's supposed to contain everything
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# (such as kernel modules) necessary to allow us to mount the root
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# file system. Once the root file system is mounted, the `real' boot
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# script can be called.
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#
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# An initramfs is a cpio archive, and may be compressed with a number
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# of algorithms.
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let
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# Some metadata on various compression programs, relevant to naming
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# the initramfs file and, if applicable, generating a u-boot image
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# from it.
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compressors = import ./initrd-compressor-meta.nix;
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# Get the basename of the actual compression program from the whole
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# compression command, for the purpose of guessing the u-boot
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# compression type and filename extension.
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compressorName = fullCommand: builtins.elemAt (builtins.match "([^ ]*/)?([^ ]+).*" fullCommand) 1;
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in
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{ stdenvNoCC, perl, cpio, ubootTools, lib, pkgsBuildHost
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# Name of the derivation (not of the resulting file!)
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, name ? "initrd"
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# Program used to compress the cpio archive; use "cat" for no compression.
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# This can also be a function which takes a package set and returns the path to the compressor,
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# such as `pkgs: "${pkgs.lzop}/bin/lzop"`.
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, compressor ? "gzip"
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, _compressorFunction ?
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if lib.isFunction compressor then compressor
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else if ! builtins.hasContext compressor && builtins.hasAttr compressor compressors then compressors.${compressor}.executable
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else _: compressor
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, _compressorExecutable ? _compressorFunction pkgsBuildHost
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, _compressorName ? compressorName _compressorExecutable
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, _compressorMeta ? compressors.${_compressorName} or {}
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# List of arguments to pass to the compressor program, or null to use its defaults
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, compressorArgs ? null
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, _compressorArgsReal ? if compressorArgs == null then _compressorMeta.defaultArgs or [] else compressorArgs
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# Filename extension to use for the compressed initramfs. This is
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# included for clarity, but $out/initrd will always be a symlink to
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# the final image.
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# If this isn't guessed, you may want to complete the metadata above and send a PR :)
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, extension ? _compressorMeta.extension or
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(throw "Unrecognised compressor ${_compressorName}, please specify filename extension")
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# List of { object = path_or_derivation; symlink = "/path"; }
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# The paths are copied into the initramfs in their nix store path
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# form, then linked at the root according to `symlink`.
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, contents
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# List of uncompressed cpio files to prepend to the initramfs. This
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# can be used to add files in specified paths without them becoming
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# symlinks to store paths.
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, prepend ? []
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# Whether to wrap the initramfs in a u-boot image.
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, makeUInitrd ? stdenvNoCC.hostPlatform.linux-kernel.target == "uImage"
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# If generating a u-boot image, the architecture to use. The default
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# guess may not align with u-boot's nomenclature correctly, so it can
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# be overridden.
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# See https://gitlab.denx.de/u-boot/u-boot/-/blob/9bfb567e5f1bfe7de8eb41f8c6d00f49d2b9a426/common/image.c#L81-106 for a list.
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, uInitrdArch ? stdenvNoCC.hostPlatform.linuxArch
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# The name of the compression, as recognised by u-boot.
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# See https://gitlab.denx.de/u-boot/u-boot/-/blob/9bfb567e5f1bfe7de8eb41f8c6d00f49d2b9a426/common/image.c#L195-204 for a list.
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# If this isn't guessed, you may want to complete the metadata above and send a PR :)
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, uInitrdCompression ? _compressorMeta.ubootName or
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(throw "Unrecognised compressor ${_compressorName}, please specify uInitrdCompression")
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}:
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let
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# !!! Move this into a public lib function, it is probably useful for others
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toValidStoreName = x: with builtins;
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lib.concatStringsSep "-" (filter (x: !(isList x)) (split "[^a-zA-Z0-9_=.?-]+" x));
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in stdenvNoCC.mkDerivation rec {
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inherit name makeUInitrd extension uInitrdArch prepend;
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${if makeUInitrd then "uInitrdCompression" else null} = uInitrdCompression;
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builder = ./make-initrd.sh;
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nativeBuildInputs = [ perl cpio ]
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++ lib.optional makeUInitrd ubootTools;
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compress = "${_compressorExecutable} ${lib.escapeShellArgs _compressorArgsReal}";
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# Pass the function through, for reuse in append-initrd-secrets. The
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# function is used instead of the string, in order to support
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# cross-compilation (append-initrd-secrets running on a different
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# architecture than what the main initramfs is built on).
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passthru = {
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compressorExecutableFunction = _compressorFunction;
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compressorArgs = _compressorArgsReal;
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};
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# !!! should use XML.
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objects = map (x: x.object) contents;
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symlinks = map (x: x.symlink) contents;
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suffices = map (x: if x ? suffix then x.suffix else "none") contents;
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# For obtaining the closure of `contents'.
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# Note: we don't use closureInfo yet, as that won't build with nix-1.x.
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# See #36268.
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exportReferencesGraph =
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lib.zipListsWith
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(x: i: [("closure-${toValidStoreName (baseNameOf x.symlink)}-${toString i}") x.object])
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contents
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(lib.range 0 (lib.length contents - 1));
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pathsFromGraph = ./paths-from-graph.pl;
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}
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