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nixpkgs/nixos/modules/system/boot/loader/generic-extlinux-compatible/extlinux-conf-builder.sh
Kai Wohlfahrt dd0a951279 nixos/hardware.deviceTree: new module
Add support for custom device-tree files, and applying overlays to them.
This is useful for supporting non-discoverable hardware, such as sensors
attached to GPIO pins on a Raspberry Pi.
2019-08-07 13:51:22 +01:00

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#! @bash@/bin/sh -e
shopt -s nullglob
export PATH=/empty
for i in @path@; do PATH=$PATH:$i/bin; done
usage() {
echo "usage: $0 -t <timeout> -c <path-to-default-configuration> [-d <boot-dir>] [-g <num-generations>]" >&2
exit 1
}
timeout= # Timeout in centiseconds
default= # Default configuration
target=/boot # Target directory
numGenerations=0 # Number of other generations to include in the menu
while getopts "t:c:d:g:" opt; do
case "$opt" in
t) # U-Boot interprets '0' as infinite and negative as instant boot
if [ "$OPTARG" -lt 0 ]; then
timeout=0
elif [ "$OPTARG" = 0 ]; then
timeout=-10
else
timeout=$((OPTARG * 10))
fi
;;
c) default="$OPTARG" ;;
d) target="$OPTARG" ;;
g) numGenerations="$OPTARG" ;;
\?) usage ;;
esac
done
[ "$timeout" = "" -o "$default" = "" ] && usage
mkdir -p $target/nixos
mkdir -p $target/extlinux
# Convert a path to a file in the Nix store such as
# /nix/store/<hash>-<name>/file to <hash>-<name>-<file>.
cleanName() {
local path="$1"
echo "$path" | sed 's|^/nix/store/||' | sed 's|/|-|g'
}
# Copy a file from the Nix store to $target/nixos.
declare -A filesCopied
copyToKernelsDir() {
local src=$(readlink -f "$1")
local dst="$target/nixos/$(cleanName $src)"
# Don't copy the file if $dst already exists. This means that we
# have to create $dst atomically to prevent partially copied
# kernels or initrd if this script is ever interrupted.
if ! test -e $dst; then
local dstTmp=$dst.tmp.$$
cp -r $src $dstTmp
mv $dstTmp $dst
fi
filesCopied[$dst]=1
result=$dst
}
# Copy its kernel, initrd and dtbs to $target/nixos, and echo out an
# extlinux menu entry
addEntry() {
local path=$(readlink -f "$1")
local tag="$2" # Generation number or 'default'
if ! test -e $path/kernel -a -e $path/initrd; then
return
fi
copyToKernelsDir "$path/kernel"; kernel=$result
copyToKernelsDir "$path/initrd"; initrd=$result
dtbDir=$(readlink -m "$path/dtbs")
if [ -e "$dtbDir" ]; then
copyToKernelsDir "$dtbDir"; dtbs=$result
fi
timestampEpoch=$(stat -L -c '%Z' $path)
timestamp=$(date "+%Y-%m-%d %H:%M" -d @$timestampEpoch)
nixosLabel="$(cat $path/nixos-version)"
extraParams="$(cat $path/kernel-params)"
echo
echo "LABEL nixos-$tag"
if [ "$tag" = "default" ]; then
echo " MENU LABEL NixOS - Default"
else
echo " MENU LABEL NixOS - Configuration $tag ($timestamp - $nixosLabel)"
fi
echo " LINUX ../nixos/$(basename $kernel)"
echo " INITRD ../nixos/$(basename $initrd)"
if [ -d "$dtbDir" ]; then
echo " FDTDIR ../nixos/$(basename $dtbs)"
fi
echo " APPEND systemConfig=$path init=$path/init $extraParams"
}
tmpFile="$target/extlinux/extlinux.conf.tmp.$$"
cat > $tmpFile <<EOF
# Generated file, all changes will be lost on nixos-rebuild!
# Change this to e.g. nixos-42 to temporarily boot to an older configuration.
DEFAULT nixos-default
MENU TITLE ------------------------------------------------------------
TIMEOUT $timeout
EOF
addEntry $default default >> $tmpFile
if [ "$numGenerations" -gt 0 ]; then
# Add up to $numGenerations generations of the system profile to the menu,
# in reverse (most recent to least recent) order.
for generation in $(
(cd /nix/var/nix/profiles && ls -d system-*-link) \
| sed 's/system-\([0-9]\+\)-link/\1/' \
| sort -n -r \
| head -n $numGenerations); do
link=/nix/var/nix/profiles/system-$generation-link
addEntry $link $generation
done >> $tmpFile
fi
mv -f $tmpFile $target/extlinux/extlinux.conf
# Remove obsolete files from $target/nixos.
for fn in $target/nixos/*; do
if ! test "${filesCopied[$fn]}" = 1; then
echo "Removing no longer needed boot file: $fn"
chmod +w -- "$fn"
rm -rf -- "$fn"
fi
done