make-initrd: various improvements

- Generate a link to the initramfs file with an appropriate file
  extension, guessed based on the compressor by default
- Use correct metadata in u-boot images if generated, up to now this
  was hardcoded to gzip and would silently generate an erroneous image
  if another compressor was specified
- Document all the parameters
- Improve cross-building compatibility, by allowing passing either a
  string as before, or a function taking a package set and returning the
  path to a compressor in the "compressor" argument of the
  function.
- Support more compression algorithms
- Place compressor executable function and arguments in passthru, for
  reuse when appending initramfses

Co-Authored-By: Dominik Xaver Hörl <hoe.dom@gmx.de>
This commit is contained in:
Linus Heckemann 2020-09-04 18:18:32 +02:00
parent 2ee35e1fce
commit 14fbf575ec
3 changed files with 135 additions and 18 deletions

View file

@ -0,0 +1,53 @@
rec {
cat = {
executable = pkgs: "cat";
ubootName = "none";
extension = ".cpio";
};
gzip = {
executable = pkgs: "${pkgs.gzip}/bin/gzip";
defaultArgs = ["-9n"];
ubootName = "gzip";
extension = ".gz";
};
bzip2 = {
executable = pkgs: "${pkgs.bzip2}/bin/bzip2";
ubootName = "bzip2";
extension = ".bz2";
};
xz = {
executable = pkgs: "${pkgs.xz}/bin/xz";
defaultArgs = ["--check=crc32" "--lzma2=dict=512KiB"];
extension = ".xz";
};
lzma = {
executable = pkgs: "${pkgs.xz}/bin/lzma";
defaultArgs = ["--check=crc32" "--lzma1=dict=512KiB"];
ubootName = "lzma";
extension = ".lzma";
};
lz4 = {
executable = pkgs: "${pkgs.lz4}/bin/lz4";
defaultArgs = ["-l"];
ubootName = "lz4";
extension = ".lz4";
};
lzop = {
executable = pkgs: "${pkgs.lzop}/bin/lzop";
ubootName = "lzo";
extension = ".lzo";
};
zstd = {
executable = pkgs: "${pkgs.zstd}/bin/zstd";
defaultArgs = ["-10"];
ubootName = "zstd";
extension = ".zst";
};
pigz = gzip // {
executable = pkgs: "${pkgs.pigz}/bin/pigz";
};
pixz = xz // {
executable = pkgs: "${pkgs.pixz}/bin/pixz";
defaultArgs = [];
};
}

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@ -1,24 +1,74 @@
# Create an initial ramdisk containing the closure of the specified
# file system objects. An initial ramdisk is used during the initial
# Create an initramfs containing the closure of the specified
# file system objects. An initramfs is used during the initial
# stages of booting a Linux system. It is loaded by the boot loader
# along with the kernel image. It's supposed to contain everything
# (such as kernel modules) necessary to allow us to mount the root
# file system. Once the root file system is mounted, the `real' boot
# script can be called.
#
# An initrd is really just a gzipped cpio archive.
#
# Symlinks are created for each top-level file system object. E.g.,
# `contents = {object = ...; symlink = /init;}' is a typical
# argument.
{ stdenvNoCC, perl, cpio, contents, ubootTools
# An initramfs is a cpio archive, and may be compressed with a number
# of algorithms.
let
# Some metadata on various compression programs, relevant to naming
# the initramfs file and, if applicable, generating a u-boot image
# from it.
compressors = import ./initrd-compressor-meta.nix;
# Get the basename of the actual compression program from the whole
# compression command, for the purpose of guessing the u-boot
# compression type and filename extension.
compressorName = fullCommand: builtins.elemAt (builtins.match "([^ ]*/)?([^ ]+).*" fullCommand) 1;
in
{ stdenvNoCC, perl, cpio, ubootTools, lib, pkgsBuildHost
# Name of the derivation (not of the resulting file!)
, name ? "initrd"
, compressor ? "gzip -9n"
# Program used to compress the cpio archive; use "cat" for no compression.
# This can also be a function which takes a package set and returns the path to the compressor,
# such as `pkgs: "${pkgs.lzop}/bin/lzop"`.
, compressor ? "gzip"
, _compressorFunction ?
if lib.isFunction compressor then compressor
else if ! builtins.hasContext compressor && builtins.hasAttr compressor compressors then compressors.${compressor}.executable
else _: compressor
, _compressorExecutable ? _compressorFunction pkgsBuildHost
, _compressorName ? compressorName _compressorExecutable
, _compressorMeta ? compressors.${_compressorName} or {}
# List of arguments to pass to the compressor program, or null to use its defaults
, compressorArgs ? null
, _compressorArgsReal ? if compressorArgs == null then _compressorMeta.defaultArgs or [] else compressorArgs
# Filename extension to use for the compressed initramfs. This is
# included for clarity, but $out/initrd will always be a symlink to
# the final image.
# If this isn't guessed, you may want to complete the metadata above and send a PR :)
, extension ? _compressorMeta.extension or
(throw "Unrecognised compressor ${_compressorName}, please specify filename extension")
# List of { object = path_or_derivation; symlink = "/path"; }
# The paths are copied into the initramfs in their nix store path
# form, then linked at the root according to `symlink`.
, contents
# List of uncompressed cpio files to prepend to the initramfs. This
# can be used to add files in specified paths without them becoming
# symlinks to store paths.
, prepend ? []
, lib
# Whether to wrap the initramfs in a u-boot image.
, makeUInitrd ? stdenvNoCC.hostPlatform.platform.kernelTarget == "uImage"
, uInitrdArch ? stdenvNoCC.hostPlatform.parsed.cpu.family
# If generating a u-boot image, the architecture to use. The default
# guess may not align with u-boot's nomenclature correctly, so it can
# be overridden.
# See https://gitlab.denx.de/u-boot/u-boot/-/blob/9bfb567e5f1bfe7de8eb41f8c6d00f49d2b9a426/common/image.c#L81-106 for a list.
, uInitrdArch ? stdenvNoCC.hostPlatform.kernelArch
# The name of the compression, as recognised by u-boot.
# See https://gitlab.denx.de/u-boot/u-boot/-/blob/9bfb567e5f1bfe7de8eb41f8c6d00f49d2b9a426/common/image.c#L195-204 for a list.
# If this isn't guessed, you may want to complete the metadata above and send a PR :)
, uInitrdCompression ? _compressorMeta.ubootName or
(throw "Unrecognised compressor ${_compressorName}, please specify uInitrdCompression")
}:
let
# !!! Move this into a public lib function, it is probably useful for others
@ -26,13 +76,26 @@ let
lib.concatStringsSep "-" (filter (x: !(isList x)) (split "[^a-zA-Z0-9_=.?-]+" x));
in stdenvNoCC.mkDerivation rec {
inherit name makeUInitrd uInitrdArch;
inherit name makeUInitrd extension uInitrdArch prepend;
${if makeUInitrd then "uinitrdCompression" else null} = uInitrdCompression;
builder = ./make-initrd.sh;
nativeBuildInputs = [ perl cpio ]
++ stdenvNoCC.lib.optional makeUInitrd ubootTools;
compress = "${_compressorExecutable} ${lib.escapeShellArgs _compressorArgsReal}";
# Pass the function through, for reuse in append-initrd-secrets. The
# function is used instead of the string, in order to support
# cross-compilation (append-initrd-secrets running on a different
# architecture than what the main initramfs is built on).
passthru = {
compressorExecutableFunction = _compressorFunction;
compressorArgs = _compressorArgsReal;
};
# !!! should use XML.
objects = map (x: x.object) contents;
symlinks = map (x: x.symlink) contents;
@ -47,6 +110,4 @@ in stdenvNoCC.mkDerivation rec {
contents
(lib.range 0 (lib.length contents - 1));
pathsFromGraph = ./paths-from-graph.pl;
inherit compressor prepend;
}

View file

@ -40,9 +40,12 @@ for PREP in $prepend; do
cat $PREP >> $out/initrd
done
(cd root && find * .[^.*] -exec touch -h -d '@1' '{}' +)
(cd root && find * .[^.*] -print0 | sort -z | cpio -o -H newc -R +0:+0 --reproducible --null | $compressor >> $out/initrd)
(cd root && find * .[^.*] -print0 | sort -z | cpio -o -H newc -R +0:+0 --reproducible --null | eval -- $compress >> "$out/initrd")
if [ -n "$makeUInitrd" ]; then
mv $out/initrd $out/initrd.gz
mkimage -A $uInitrdArch -O linux -T ramdisk -C gzip -d $out/initrd.gz $out/initrd
mkimage -A $uInitrdArch -O linux -T ramdisk -C "$uInitrdCompression" -d $out/initrd"$extension" $out/initrd.img
# Compatibility symlink
ln -s "initrd.img" "$out/initrd"
else
ln -s "initrd" "$out/initrd$extension"
fi