fs/initramfs: refactor with fs/cpio
An initramfs is in fact the same as a cpio archive, but embedded in the kernel. So instead of duplicating the cpio infrastructure, we can simply build images/rootfs.cpio and link that into the kernel. Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
This commit is contained in:
Arnout Vandecappelle (Essensium/Mind)
Peter Korsgaard
parent
3fac21ef8d
commit
13a3afc536
@ -1,20 +1,21 @@
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config BR2_TARGET_ROOTFS_INITRAMFS
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bool "initramfs for initial ramdisk of linux kernel"
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depends on BR2_LINUX_KERNEL
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select BR2_TARGET_ROOTFS_CPIO
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help
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Integrate the root filesystem generated by Buildroot as an
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initramfs inside the kernel image. This integration will
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take place automatically.
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The rootfs.initramfs file generated in the images/ directory
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is only a text file describing the contents of the initramfs
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in a format understood by the CONFIG_INITRAMFS_SOURCE kernel
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configuration option.
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A rootfs.cpio file will be generated in the images/ directory.
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This is the archive that will be included in the kernel image.
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The rootfs in the kernel will always be gzip'ed, regardless
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of how buildroot's cpio archive is configured.
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Note that enabling initramfs together with other filesystem
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Note that enabling initramfs together with another filesystem
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formats doesn't make sense: you would end up having two
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identical root filesystems, one embedded inside the kernel
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image, and one separatly.
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image, and one separately.
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comment "initramfs requires a Linux kernel to be built"
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depends on !BR2_LINUX_KERNEL
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@ -1,203 +0,0 @@
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#!/bin/sh
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# Copyright (C) Martin Schlemmer <azarah@nosferatu.za.org>
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# Released under the terms of the GNU GPL
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#
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# Generate a newline separated list of entries from the file/directory
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# supplied as an argument.
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#
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# If a file/directory is not supplied then generate a small dummy file.
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#
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# The output is suitable for gen_init_cpio built from usr/gen_init_cpio.c.
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#
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default_initramfs() {
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cat <<-EOF
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# This is a very simple, default initramfs
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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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dir /root 0700 0 0
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EOF
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}
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filetype() {
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local argv1="$1"
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# symlink test must come before file test
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if [ -L "$argv1" ]; then
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echo "slink"
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elif [ -f "$argv1" ]; then
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echo "file"
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elif [ -d "$argv1" ]; then
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echo "dir"
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elif [ -b "$argv1" -o -c "$argv1" ]; then
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echo "nod"
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elif [ -p "$argv1" ]; then
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echo "pipe"
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elif [ -S "$argv1" ]; then
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echo "sock"
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else
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echo "invalid"
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fi
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return 0
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}
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print_mtime() {
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local argv1="$1"
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local mymtime="0"
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if [ -e "$argv1" ]; then
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mymtime=$(find "$argv1" -printf "%T@\n" | sort -r | head -n 1)
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fi
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echo "# Last modified: $mymtime"
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echo
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}
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parse() {
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local location="$1"
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local name=$(echo "$location" | sed -e "s,$srcdir,,")
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# change '//' into '/'
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name=$(echo $name | sed -e 's,/[/]*,/,g')
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local mode="$2"
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local uid="$3"
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local gid="$4"
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local ftype=$(filetype "$location")
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# remap uid/gid to 0 if necessary
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[ "x$uid" != "x" ] && [ $uid -eq $root_uid ] && uid=0
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[ "x$gid" != "x" ] && [ $gid -eq $root_gid ] && gid=0
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local str="$mode $uid $gid"
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[ "$ftype" = "invalid" ] && return 0
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[ "$location" = "$srcdir" ] && return 0
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case "$ftype" in
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"file")
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str="$ftype $name $location $str"
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;;
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"nod")
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local devtype=
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local maj=$(LC_ALL=C ls -l "$location" | \
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awk '{sub(/,/, "", $5); print $5}')
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local min=$(LC_ALL=C ls -l "$location" | \
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awk '{print $6}')
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if [ -b "$location" ]; then
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devtype="b"
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else
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devtype="c"
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fi
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str="$ftype $name $str $devtype $maj $min"
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;;
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"slink")
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local target=$(LC_ALL=C ls -l "$location" | \
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awk '{print $11}')
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str="$ftype $name $target $str"
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;;
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*)
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str="$ftype $name $str"
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;;
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esac
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echo "$str"
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return 0
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}
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usage() {
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printf "Usage:\n"
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printf "$0 [ [-u <root_uid>] [-g <root_gid>] [-d | <cpio_source>] ] . . .\n"
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printf "\n"
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printf -- "-u <root_uid> User ID to map to user ID 0 (root).\n"
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printf " <root_uid> is only meaningful if <cpio_source>\n"
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printf " is a directory.\n"
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printf -- "-g <root_gid> Group ID to map to group ID 0 (root).\n"
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printf " <root_gid> is only meaningful if <cpio_source>\n"
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printf " is a directory.\n"
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printf "<cpio_source> File list or directory for cpio archive.\n"
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printf " If <cpio_source> is not provided then a\n"
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printf " a default list will be output.\n"
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printf -- "-d Output the default cpio list. If no <cpio_source>\n"
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printf " is given then the default cpio list will be output.\n"
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printf "\n"
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printf "All options may be repeated and are interpreted sequentially\n"
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printf "and immediately. -u and -g states are preserved across\n"
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printf "<cpio_source> options so an explicit \"-u 0 -g 0\" is required\n"
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printf "to reset the root/group mapping.\n"
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}
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build_list() {
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printf "\n#####################\n# $cpio_source\n"
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if [ -f "$cpio_source" ]; then
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print_mtime "$cpio_source"
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cat "$cpio_source"
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elif [ -d "$cpio_source" ]; then
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srcdir=$(echo "$cpio_source" | sed -e 's://*:/:g;s:/$::')
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dirlist=$(find "$srcdir" -printf "%p %m %U %G\n" 2>/dev/null)
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# If $dirlist is only one line, then the directory is empty
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if [ "$(echo "$dirlist" | wc -l)" -gt 1 ]; then
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print_mtime "$cpio_source"
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echo "$dirlist" | \
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while read x; do
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parse $x
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done
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else
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# Failsafe in case directory is empty
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default_initramfs
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fi
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else
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echo " $0: Cannot open '$cpio_source'" >&2
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exit 1
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fi
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}
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root_uid=0
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root_gid=0
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while [ $# -gt 0 ]; do
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arg="$1"
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shift
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case "$arg" in
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"-u")
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root_uid="$1"
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shift
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;;
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"-g")
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root_gid="$1"
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shift
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;;
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"-d")
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default_list="$arg"
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default_initramfs
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;;
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"-h")
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usage
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exit 0
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;;
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*)
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case "$arg" in
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"-"*)
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printf "ERROR: unknown option \"$arg\"\n" >&2
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printf "If the filename validly begins with '-', then it must be prefixed\n" >&2
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printf "by './' so that it won't be interpreted as an option." >&2
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printf "\n" >&2
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usage >&2
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exit 1
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;;
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*)
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cpio_source="$arg"
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build_list
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;;
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esac
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;;
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esac
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done
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# spit out the default cpio list if a source hasn't been specified
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[ -z "$cpio_source" -a -z "$default_list" ] && default_initramfs
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exit 0
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@ -1,7 +0,0 @@
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#!/bin/sh
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# devtmpfs does not get automounted for initramfs
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/bin/mount -t devtmpfs devtmpfs /dev
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exec 0</dev/console
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exec 1>/dev/console
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exec 2>/dev/console
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exec /sbin/init $*
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@ -1,36 +1,23 @@
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#############################################################
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#
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# Make a initramfs_list file to be used by gen_init_cpio
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# gen_init_cpio is part of the 2.6 linux kernels to build an
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# initial ramdisk filesystem based on cpio
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# Build a kernel with an integrated initial ramdisk
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# filesystem based on cpio.
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#
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#############################################################
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ifeq ($(BR2_ROOTFS_DEVICE_CREATION_STATIC),y)
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define ROOTFS_INITRAMFS_ADD_INIT
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if [ ! -e $(TARGET_DIR)/init ]; then \
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ln -sf sbin/init $(TARGET_DIR)/init; \
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fi
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endef
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else
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# devtmpfs does not get automounted when initramfs is used.
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# Add a pre-init script to mount it before running init
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define ROOTFS_INITRAMFS_ADD_INIT
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if [ ! -e $(TARGET_DIR)/init ]; then \
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$(INSTALL) -m 0755 fs/initramfs/init $(TARGET_DIR)/init; \
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fi
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endef
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endif # BR2_ROOTFS_DEVICE_CREATION_STATIC
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ROOTFS_INITRAMFS_PRE_GEN_HOOKS += ROOTFS_INITRAMFS_ADD_INIT
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define ROOTFS_INITRAMFS_CMD
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$(SHELL) fs/initramfs/gen_initramfs_list.sh -u 0 -g 0 $(TARGET_DIR) > $$@
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endef
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ROOTFS_INITRAMFS_DEPENDENCIES += rootfs-cpio
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ROOTFS_INITRAMFS_POST_TARGETS += linux26-rebuild-with-initramfs
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$(eval $(call ROOTFS_TARGET,initramfs))
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# The generic fs infrastructure isn't very useful here.
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rootfs-initramfs: $(ROOTFS_INITRAMFS_DEPENDENCIES) $(ROOTFS_INITRAMFS_POST_TARGETS)
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rootfs-initramfs-show-depends:
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@echo $(ROOTFS_INITRAMFS_DEPENDENCIES)
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ifeq ($(BR2_TARGET_ROOTFS_INITRAMFS),y)
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TARGETS += rootfs-initramfs
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endif
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@ -126,13 +126,13 @@ define LINUX_CONFIGURE_CMDS
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$(call KCONFIG_ENABLE_OPT,CONFIG_AEABI,$(@D)/.config),
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$(call KCONFIG_DISABLE_OPT,CONFIG_AEABI,$(@D)/.config))
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# As the kernel gets compiled before root filesystems are
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# built, we create a fake initramfs file list. It'll be
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# replaced later by the real list, and the kernel will be
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# built, we create a fake cpio file. It'll be
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# replaced later by the real cpio archive, and the kernel will be
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# rebuilt using the linux26-rebuild-with-initramfs target.
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$(if $(BR2_TARGET_ROOTFS_INITRAMFS),
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touch $(BINARIES_DIR)/rootfs.initramfs
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touch $(BINARIES_DIR)/rootfs.cpio
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$(call KCONFIG_ENABLE_OPT,CONFIG_BLK_DEV_INITRD,$(@D)/.config)
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$(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_SOURCE,\"$(BINARIES_DIR)/rootfs.initramfs\",$(@D)/.config)
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$(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_SOURCE,\"$(BINARIES_DIR)/rootfs.cpio\",$(@D)/.config)
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$(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_UID,0,$(@D)/.config)
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$(call KCONFIG_SET_OPT,CONFIG_INITRAMFS_ROOT_GID,0,$(@D)/.config)
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$(call KCONFIG_DISABLE_OPT,CONFIG_INITRAMFS_COMPRESSION_NONE,$(@D)/.config)
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@ -190,13 +190,10 @@ linux-savedefconfig linux26-savedefconfig: dirs $(LINUX_DIR)/.stamp_configured
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$(MAKE) $(LINUX_MAKE_FLAGS) -C $(LINUX_DIR) \
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$(subst linux-,,$(subst linux26-,,$@))
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# Support for rebuilding the kernel after the initramfs file list has
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# been generated in $(BINARIES_DIR)/rootfs.initramfs.
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$(LINUX_DIR)/.stamp_initramfs_rebuilt: $(LINUX_DIR)/.stamp_target_installed $(LINUX_DIR)/.stamp_images_installed $(BINARIES_DIR)/rootfs.initramfs
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# Support for rebuilding the kernel after the cpio archive has
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# been generated in $(BINARIES_DIR)/rootfs.cpio.
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$(LINUX_DIR)/.stamp_initramfs_rebuilt: $(LINUX_DIR)/.stamp_target_installed $(LINUX_DIR)/.stamp_images_installed $(BINARIES_DIR)/rootfs.cpio
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@$(call MESSAGE,"Rebuilding kernel with initramfs")
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# Remove the previously generated initramfs which was empty,
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# to make sure the kernel will actually regenerate it.
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$(RM) -f $(@D)/usr/initramfs_data.cpio*
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# Build the kernel.
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$(TARGET_MAKE_ENV) $(MAKE) $(LINUX_MAKE_FLAGS) -C $(@D) $(LINUX_IMAGE_NAME)
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# Copy the kernel image to its final destination
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