165 lines
9.5 KiB
Bash
Executable file
165 lines
9.5 KiB
Bash
Executable file
# This script is called by ./xen-dom0.nix to create the Xen boot entries.
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# shellcheck shell=bash
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# Handle input argument and exit if the flag is invalid. See virtualisation.xen.efi.bootBuilderVerbosity below.
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[[ $# -ne 1 ]] && echo -e "\e[1;31merror:\e[0m xenBootBuilder must be called with exactly one verbosity argument. See the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option." && exit 1
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case "$1" in
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"quiet") true ;;
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"default" | "info") echo -n "Installing Xen Project Hypervisor boot entries..." ;;
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"debug") echo -e "\e[1;34mxenBootBuilder:\e[0m called with the '$1' flag" ;;
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*)
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echo -e "\e[1;31merror:\e[0m xenBootBuilder was called with an invalid argument. See the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option."
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exit 2
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;;
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esac
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# Get the current Xen generations and store them in an array. This will be used
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# for displaying the diff later, if xenBootBuilder was called with `info`.
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# We also delete the current Xen entries here, as they'll be rebuilt later if
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# the corresponding NixOS generation still exists.
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mapfile -t preGenerations < <(find "$efiMountPoint"/loader/entries -type f -name 'xen-*.conf' | sort -V | sed 's_/loader/entries/nixos_/loader/entries/xen_g;s_^.*/xen_xen_g;s_.conf$__g')
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if [ "$1" = "debug" ]; then
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if ((${#preGenerations[@]} == 0)); then
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echo -e "\e[1;34mxenBootBuilder:\e[0m no previous Xen entries."
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else
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echo -e "\e[1;34mxenBootBuilder:\e[0m deleting the following stale xen entries:" && for debugGen in "${preGenerations[@]}"; do echo " - $debugGen"; done
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fi
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fi
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# Cleanup all Xen entries.
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rm -f "$efiMountPoint"/{loader/entries/xen-*.conf,efi/nixos/xen-*.efi}
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# Main array for storing which generations exist in $efiMountPoint after
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# systemd-boot-builder.py builds the main entries.
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mapfile -t gens < <(find "$efiMountPoint"/loader/entries -type f -name 'nixos-*.conf' | sort -V)
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[ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m found the following NixOS boot entries:" && for debugGen in "${gens[@]}"; do echo " - $debugGen"; done
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# This is the main loop that installs the Xen entries.
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for gen in "${gens[@]}"; do
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# We discover the path to Bootspec through the init attribute in the entries,
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# as it is equivalent to $toplevel/init.
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bootspecFile="$(sed -nr 's/^options init=(.*)\/init.*$/\1/p' "$gen")/boot.json"
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[ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m processing bootspec file $bootspecFile"
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# We do nothing if the Bootspec for the current $gen does not contain the Xen
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# extension, which is added as a configuration attribute below.
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if grep -sq '"org.xenproject.bootspec.v1"' "$bootspecFile"; then
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[ "$1" = "debug" ] && echo -e " \e[1;32msuccess:\e[0m found Xen entries in $gen."
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# TODO: Support DeviceTree booting. Xen has some special handling for DeviceTree
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# attributes, which will need to be translated in a boot script similar to this
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# one. Having a DeviceTree entry is rare, and it is not always required for a
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# successful boot, so we don't fail here, only warn with `debug`.
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if grep -sq '"devicetree"' "$bootspecFile"; then
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echo -e "\n\e[1;33mwarning:\e[0m $gen has a \e[1;34morg.nixos.systemd-boot.devicetree\e[0m Bootspec entry. Xen currently does not support DeviceTree, so this value will be ignored in the Xen boot entries, which may cause them to \e[1;31mfail to boot\e[0m."
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else
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[ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m no DeviceTree entries found in $gen."
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fi
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# Prepare required attributes for `xen.cfg/xen.conf`. It inherits the name of
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# the corresponding nixos generation, substituting `nixos` with `xen`:
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# `xen-$profile-generation-$number-specialisation-$specialisation.{cfg,conf}`
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xenGen=$(echo "$gen" | sed 's_/loader/entries/nixos_/loader/entries/xen_g;s_^.*/xen_xen_g;s_.conf$__g')
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bootParams=$(jq -re '."org.xenproject.bootspec.v1".xenParams | join(" ")' "$bootspecFile")
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kernel=$(jq -re '."org.nixos.bootspec.v1".kernel | sub("^/nix/store/"; "") | sub("/bzImage"; "-bzImage.efi")' "$bootspecFile")
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kernelParams=$(jq -re '."org.nixos.bootspec.v1".kernelParams | join(" ")' "$bootspecFile")
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initrd=$(jq -re '."org.nixos.bootspec.v1".initrd | sub("^/nix/store/"; "") | sub("/initrd"; "-initrd.efi")' "$bootspecFile")
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init=$(jq -re '."org.nixos.bootspec.v1".init' "$bootspecFile")
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title=$(sed -nr 's/^title (.*)$/\1/p' "$gen")
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version=$(sed -nr 's/^version (.*)$/\1/p' "$gen")
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machineID=$(sed -nr 's/^machine-id (.*)$/\1/p' "$gen")
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sortKey=$(sed -nr 's/^sort-key (.*)$/\1/p' "$gen")
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# Write `xen.cfg` to a temporary location prior to UKI creation.
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tmpCfg=$(mktemp)
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[ "$1" = "debug" ] && echo -ne "\e[1;34mxenBootBuilder:\e[0m writing $xenGen.cfg to temporary file..."
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cat > "$tmpCfg" << EOF
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[global]
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default=xen
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[xen]
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options=$bootParams
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kernel=$kernel init=$init $kernelParams
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ramdisk=$initrd
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EOF
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[ "$1" = "debug" ] && echo -e "done."
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# Create Xen UKI for $generation. Most of this is lifted from
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# https://xenbits.xenproject.org/docs/unstable/misc/efi.html.
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[ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m making Xen UKI..."
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xenEfi=$(jq -re '."org.xenproject.bootspec.v1".xen' "$bootspecFile")
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padding=$(objdump --header --section=".pad" "$xenEfi" | awk '/\.pad/ { printf("0x%016x\n", strtonum("0x"$3) + strtonum("0x"$4))};')
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[ "$1" = "debug" ] && echo " - padding: $padding"
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objcopy \
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--add-section .config="$tmpCfg" \
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--change-section-vma .config="$padding" \
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"$xenEfi" \
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"$efiMountPoint"/EFI/nixos/"$xenGen".efi
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[ "$1" = "debug" ] && echo -e " - \e[1;32msuccessfully built\e[0m $xenGen.efi"
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rm -f "$tmpCfg"
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# Write `xen.conf`.
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[ "$1" = "debug" ] && echo -ne "\e[1;34mxenBootBuilder:\e[0m writing $xenGen.conf to EFI System Partition..."
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cat > "$efiMountPoint"/loader/entries/"$xenGen".conf << EOF
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title $title (with Xen Hypervisor)
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version $version
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efi /EFI/nixos/$xenGen.efi
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machine-id $machineID
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sort-key $sortKey
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EOF
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[ "$1" = "debug" ] && echo -e "done."
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# Sometimes, garbage collection weirdness causes a generation to still exist in
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# the loader entries, but its Bootspec file was deleted. We consider such a
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# generation to be invalid, but we don't write extra code to handle this
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# situation, as supressing grep's error messages above is quite enough, and the
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# error message below is still technically correct, as no Xen can be found in
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# something that does not exist.
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else
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[ "$1" = "debug" ] && echo -e " \e[1;33mwarning:\e[0m \e[1;31mno Xen found\e[0m in $gen."
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fi
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done
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# Counterpart to the preGenerations array above. We use it to diff the
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# generations created/deleted when callled with the `info` argument.
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mapfile -t postGenerations < <(find "$efiMountPoint"/loader/entries -type f -name 'xen-*.conf' | sort -V | sed 's_/loader/entries/nixos_/loader/entries/xen_g;s_^.*/xen_xen_g;s_.conf$__g')
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# In the event the script does nothing, guide the user to debug, as it'll only
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# ever run when Xen is enabled, and it makes no sense to enable Xen and not have
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# any hypervisor boot entries.
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if ((${#postGenerations[@]} == 0)); then
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case "$1" in
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"default" | "info") echo "none found." && echo -e "If you believe this is an error, set the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option to \e[1;34m\"debug\"\e[0m and rebuild to print debug logs." ;;
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"debug") echo -e "\e[1;34mxenBootBuilder:\e[0m wrote \e[1;31mno generations\e[0m. Most likely, there were no generations with a valid \e[1;34morg.xenproject.bootspec.v1\e[0m entry." ;;
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esac
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# If the script is successful, change the default boot, say "done.", write a
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# diff, or print the total files written, depending on the argument this script
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# was called with. We use some dumb dependencies here, like `diff` or `bat` for
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# colourisation, but they're only included with the `info` argument.
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#
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# It's also fine to change the default here, as this runs after the
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# `systemd-boot-builder.py` script, which overwrites the file, and this script
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# does not run after an user disables the Xen module.
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else
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sed --in-place 's/^default nixos-/default xen-/g' "$efiMountPoint"/loader/loader.conf
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case "$1" in
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"default" | "info") echo "done." ;;
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"debug") echo -e "\e[1;34mxenBootBuilder:\e[0m \e[1;32msuccessfully wrote\e[0m the following generations:" && for debugGen in "${postGenerations[@]}"; do echo " - $debugGen"; done ;;
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esac
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if [ "$1" = "info" ]; then
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if [[ ${#preGenerations[@]} == "${#postGenerations[@]}" ]]; then
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echo -e "\e[1;33mNo Change:\e[0m Xen Project Hypervisor boot entries were refreshed, but their contents are identical."
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else
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echo -e "\e[1;32mSuccess:\e[0m Changed the following boot entries:"
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# We briefly unset errexit and pipefail here, as GNU diff has no option to not fail when files differ.
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set +o errexit
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set +o pipefail
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diff <(echo "${preGenerations[*]}" | tr ' ' '\n') <(echo "${postGenerations[*]}" | tr ' ' '\n') -U 0 | grep --invert-match --extended-regexp '^(@@|---|\+\+\+).*' | sed '1{/^-$/d}' | bat --language diff --theme ansi --paging=never --plain
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true
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set -o errexit
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set -o pipefail
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fi
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fi
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fi
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