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nixos/xen: refactor dom0 configuration (NixOS#324911)
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,165 @@ | ||
| # This script is called by ./xen-dom0.nix to create the Xen boot entries. | ||
| # shellcheck shell=bash | ||
|
|
||
| # Handle input argument and exit if the flag is invalid. See virtualisation.xen.efi.bootBuilderVerbosity below. | ||
| [[ $# -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 | ||
| case "$1" in | ||
| "quiet") true ;; | ||
| "default" | "info") echo -n "Installing Xen Hypervisor boot entries..." ;; | ||
| "debug") echo -e "\e[1;34mxenBootBuilder:\e[0m called with the '$1' flag" ;; | ||
| *) | ||
| echo -e "\e[1;31merror:\e[0m xenBootBuilder was called with an invalid argument. See the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option." | ||
| exit 2 | ||
| ;; | ||
| esac | ||
|
|
||
| # Get the current Xen generations and store them in an array. This will be used | ||
| # for displaying the diff later, if xenBootBuilder was called with `info`. | ||
| # We also delete the current Xen entries here, as they'll be rebuilt later if | ||
| # the corresponding NixOS generation still exists. | ||
| mapfile -t preGenerations < <(find "$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') | ||
| if [ "$1" = "debug" ]; then | ||
| if ((${#preGenerations[@]} == 0)); then | ||
| echo -e "\e[1;34mxenBootBuilder:\e[0m no previous Xen entries." | ||
| else | ||
| echo -e "\e[1;34mxenBootBuilder:\e[0m deleting the following stale xen entries:" && for debugGen in "${preGenerations[@]}"; do echo " - $debugGen"; done | ||
| fi | ||
| fi | ||
|
|
||
| # Cleanup all Xen entries. | ||
| rm -f "$efiMountPoint"/{loader/entries/xen-*.conf,efi/nixos/xen-*.efi} | ||
|
|
||
| # Main array for storing which generations exist in $efiMountPoint after | ||
| # systemd-boot-builder.py builds the main entries. | ||
| mapfile -t gens < <(find "$efiMountPoint"/loader/entries -type f -name 'nixos-*.conf' | sort -V) | ||
| [ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m found the following NixOS boot entries:" && for debugGen in "${gens[@]}"; do echo " - $debugGen"; done | ||
|
|
||
| # This is the main loop that installs the Xen entries. | ||
| for gen in "${gens[@]}"; do | ||
|
|
||
| # We discover the path to Bootspec through the init attribute in the entries, | ||
| # as it is equivalent to $toplevel/init. | ||
| bootspecFile="$(sed -nr 's/^options init=(.*)\/init.*$/\1/p' "$gen")/boot.json" | ||
| [ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m processing bootspec file $bootspecFile" | ||
|
|
||
| # We do nothing if the Bootspec for the current $gen does not contain the Xen | ||
| # extension, which is added as a configuration attribute below. | ||
| if grep -sq '"org.xenproject.bootspec.v1"' "$bootspecFile"; then | ||
| [ "$1" = "debug" ] && echo -e " \e[1;32msuccess:\e[0m found Xen entries in $gen." | ||
|
|
||
| # TODO: Support DeviceTree booting. Xen has some special handling for DeviceTree | ||
| # attributes, which will need to be translated in a boot script similar to this | ||
| # one. Having a DeviceTree entry is rare, and it is not always required for a | ||
| # successful boot, so we don't fail here, only warn with `debug`. | ||
| if grep -sq '"devicetree"' "$bootspecFile"; then | ||
| 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." | ||
| else | ||
| [ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m no DeviceTree entries found in $gen." | ||
| fi | ||
|
|
||
| # Prepare required attributes for `xen.cfg/xen.conf`. It inherits the name of | ||
| # the corresponding nixos generation, substituting `nixos` with `xen`: | ||
| # `xen-$profile-generation-$number-specialisation-$specialisation.{cfg,conf}` | ||
| xenGen=$(echo "$gen" | sed 's_/loader/entries/nixos_/loader/entries/xen_g;s_^.*/xen_xen_g;s_.conf$__g') | ||
| bootParams=$(jq -re '."org.xenproject.bootspec.v1".xenParams | join(" ")' "$bootspecFile") | ||
| kernel=$(jq -re '."org.nixos.bootspec.v1".kernel | sub("^/nix/store/"; "") | sub("/bzImage"; "-bzImage.efi")' "$bootspecFile") | ||
| kernelParams=$(jq -re '."org.nixos.bootspec.v1".kernelParams | join(" ")' "$bootspecFile") | ||
| initrd=$(jq -re '."org.nixos.bootspec.v1".initrd | sub("^/nix/store/"; "") | sub("/initrd"; "-initrd.efi")' "$bootspecFile") | ||
| init=$(jq -re '."org.nixos.bootspec.v1".init' "$bootspecFile") | ||
| title=$(sed -nr 's/^title (.*)$/\1/p' "$gen") | ||
| version=$(sed -nr 's/^version (.*)$/\1/p' "$gen") | ||
| machineID=$(sed -nr 's/^machine-id (.*)$/\1/p' "$gen") | ||
| sortKey=$(sed -nr 's/^sort-key (.*)$/\1/p' "$gen") | ||
|
|
||
| # Write `xen.cfg` to a temporary location prior to UKI creation. | ||
| tmpCfg=$(mktemp) | ||
| [ "$1" = "debug" ] && echo -ne "\e[1;34mxenBootBuilder:\e[0m writing $xenGen.cfg to temporary file..." | ||
| cat > "$tmpCfg" << EOF | ||
| [global] | ||
| default=xen | ||
| [xen] | ||
| options=$bootParams | ||
| kernel=$kernel init=$init $kernelParams | ||
| ramdisk=$initrd | ||
| EOF | ||
| [ "$1" = "debug" ] && echo -e "done." | ||
|
|
||
| # Create Xen UKI for $generation. Most of this is lifted from | ||
| # https://xenbits.xenproject.org/docs/unstable/misc/efi.html. | ||
| [ "$1" = "debug" ] && echo -e "\e[1;34mxenBootBuilder:\e[0m making Xen UKI..." | ||
| xenEfi=$(jq -re '."org.xenproject.bootspec.v1".xen' "$bootspecFile") | ||
| padding=$(objdump --header --section=".pad" "$xenEfi" | awk '/\.pad/ { printf("0x%016x\n", strtonum("0x"$3) + strtonum("0x"$4))};') | ||
| [ "$1" = "debug" ] && echo " - padding: $padding" | ||
| objcopy \ | ||
| --add-section .config="$tmpCfg" \ | ||
| --change-section-vma .config="$padding" \ | ||
| "$xenEfi" \ | ||
| "$efiMountPoint"/EFI/nixos/"$xenGen".efi | ||
| [ "$1" = "debug" ] && echo -e " - \e[1;32msuccessfully built\e[0m $xenGen.efi" | ||
| rm -f "$tmpCfg" | ||
|
|
||
| # Write `xen.conf`. | ||
| [ "$1" = "debug" ] && echo -ne "\e[1;34mxenBootBuilder:\e[0m writing $xenGen.conf to EFI System Partition..." | ||
| cat > "$efiMountPoint"/loader/entries/"$xenGen".conf << EOF | ||
| title $title (with Xen Hypervisor) | ||
| version $version | ||
| efi /EFI/nixos/$xenGen.efi | ||
| machine-id $machineID | ||
| sort-key $sortKey | ||
| EOF | ||
| [ "$1" = "debug" ] && echo -e "done." | ||
|
|
||
| # Sometimes, garbage collection weirdness causes a generation to still exist in | ||
| # the loader entries, but its Bootspec file was deleted. We consider such a | ||
| # generation to be invalid, but we don't write extra code to handle this | ||
| # situation, as supressing grep's error messages above is quite enough, and the | ||
| # error message below is still technically correct, as no Xen can be found in | ||
| # something that does not exist. | ||
| else | ||
| [ "$1" = "debug" ] && echo -e " \e[1;33mwarning:\e[0m \e[1;31mno Xen found\e[0m in $gen." | ||
| fi | ||
| done | ||
|
|
||
| # Counterpart to the preGenerations array above. We use it to diff the | ||
| # generations created/deleted when callled with the `info` argument. | ||
| mapfile -t postGenerations < <(find "$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$__g') | ||
|
|
||
| # In the event the script does nothing, guide the user to debug, as it'll only | ||
| # ever run when Xen is enabled, and it makes no sense to enable Xen and not have | ||
| # any hypervisor boot entries. | ||
| if ((${#postGenerations[@]} == 0)); then | ||
| case "$1" in | ||
| "default" | "info") echo "none found." && echo -e "If you believe this is an error, set the \e[1;34mvirtualisation.xen.efi.bootBuilderVerbosity\e[0m option to \e[1;34m\"debug\"\e[0m and rebuild to print debug logs." ;; | ||
| "debug") echo -e "\e[1;34mxenBootBuilder:\e[0m wrote \e[1;31mno generations\e[0m. Most likely, there were no generations with a valid \e[1;34morg.xenproject.bootspec.v1\e[0m entry." ;; | ||
| esac | ||
|
|
||
| # If the script is successful, change the default boot, say "done.", write a | ||
| # diff, or print the total files written, depending on the argument this script | ||
| # was called with. We use some dumb dependencies here, like `diff` or `bat` for | ||
| # colourisation, but they're only included with the `info` argument. | ||
| # | ||
| # It's also fine to change the default here, as this runs after the | ||
| # `systemd-boot-builder.py` script, which overwrites the file, and this script | ||
| # does not run after an user disables the Xen module. | ||
| else | ||
| sed --in-place 's/^default nixos-/default xen-/g' "$efiMountPoint"/loader/loader.conf | ||
| case "$1" in | ||
| "default" | "info") echo "done." ;; | ||
| "debug") echo -e "\e[1;34mxenBootBuilder:\e[0m \e[1;32msuccessfully wrote\e[0m the following generations:" && for debugGen in "${postGenerations[@]}"; do echo " - $debugGen"; done ;; | ||
| esac | ||
| if [ "$1" = "info" ]; then | ||
| if [[ ${#preGenerations[@]} == "${#postGenerations[@]}" ]]; then | ||
| echo -e "\e[1;33mNo Change:\e[0m Xen Hypervisor boot entries were refreshed, but their contents are identical." | ||
| else | ||
| echo -e "\e[1;32mSuccess:\e[0m Changed the following boot entries:" | ||
| # We briefly unset errexit and pipefail here, as GNU diff has no option to not fail when files differ. | ||
| set +o errexit | ||
| set +o pipefail | ||
| 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 | ||
| true | ||
| set -o errexit | ||
| set -o pipefail | ||
| fi | ||
| fi | ||
| fi |
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