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systemd-boot: introduce options to set a sort-key for systemd-boot entries

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Without sort-keys specified on entries, the entries are sorted only by
file name (in decreasing order, so starting at the end of the alphabet!),
without taking any other fields into account (see
[the boot loader specification reference][1]).
Moreover, entries without a sort-key are always ordered after all
entries with a sort-key, so by not adding a sort-key to the NixOS ones,
we cannot add a sort-key to any other entry while keeping it below the
NixOS entries.

So currently we have options to set the file names for additional entries like
memtest and netbootxyz.
However, as mentioned above, the sorting by file name is not very intuitive and
actually sorts in the opposite order of what is currently mentioned in the option
descriptions.

With this commit, we set a configurable sort-key on all NixOS entries,
and add options for setting the sort-keys for the memtest and netbootxyz
entries.
The sorting by sort-key is more intuitive (it starts at the start of the
alphabet) and also takes into account the machine-id and version for entries
with identical sort-keys.

We use a bootspec extension to store the sort keys, which allows us to
redefine the sort key for individual specialisations without needing any
special casing.

[1]: https://uapi-group.org/specifications/specs/boot_loader_specification/#sorting
This commit is contained in:
r-vdp 2024-01-24 18:15:28 +01:00
parent 0267739e11
commit a8ab8b59a7
No known key found for this signature in database
3 changed files with 88 additions and 24 deletions
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11
nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py
View File

@ -43,6 +43,7 @@ class BootSpec:
system: str
toplevel: str
specialisations: Dict[str, "BootSpec"]
sortKey: str
initrdSecrets: str | None = None
@ -73,6 +74,7 @@ def system_dir(profile: str | None, generation: int, specialisation: str | None)
return d
BOOT_ENTRY = """title {title}
sort-key {sort_key}
version Generation {generation} {description}
linux {kernel}
initrd {initrd}
@ -123,7 +125,13 @@ def get_bootspec(profile: str | None, generation: int) -> BootSpec:
def bootspec_from_json(bootspec_json: Dict) -> BootSpec:
specialisations = bootspec_json['org.nixos.specialisation.v1']
specialisations = {k: bootspec_from_json(v) for k, v in specialisations.items()}
return BootSpec(**bootspec_json['org.nixos.bootspec.v1'], specialisations=specialisations)
systemdBootExtension = bootspec_json.get('org.nixos.systemd-boot', {})
sortKey = systemdBootExtension.get('sortKey', 'nixos')
return BootSpec(
**bootspec_json['org.nixos.bootspec.v1'],
specialisations=specialisations,
sortKey=sortKey
)
def copy_from_file(file: str, dry_run: bool = False) -> str:
@ -170,6 +178,7 @@ def write_entry(profile: str | None, generation: int, specialisation: str | None
with open(tmp_path, 'w') as f:
f.write(BOOT_ENTRY.format(title=title,
sort_key=bootspec.sortKey,
generation=generation,
kernel=kernel,
initrd=initrd,

73
nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
View File

@ -87,6 +87,16 @@ in {
imports =
[ (mkRenamedOptionModule [ "boot" "loader" "gummiboot" "enable" ] [ "boot" "loader" "systemd-boot" "enable" ])
(lib.mkChangedOptionModule
[ "boot" "loader" "systemd-boot" "memtest86" "entryFilename" ]
[ "boot" "loader" "systemd-boot" "memtest86" "sortKey" ]
(config: lib.strings.removeSuffix ".conf" config.boot.loader.systemd-boot.memtest86.entryFilename)
)
(lib.mkChangedOptionModule
[ "boot" "loader" "systemd-boot" "netbootxyz" "entryFilename" ]
[ "boot" "loader" "systemd-boot" "netbootxyz" "sortKey" ]
(config: lib.strings.removeSuffix ".conf" config.boot.loader.systemd-boot.netbootxyz.entryFilename)
)
];
options.boot.loader.systemd-boot = {
@ -102,6 +112,35 @@ in {
'';
};
sortKey = mkOption {
default = "nixos";
type = lib.types.str;
description = ''
The sort key used for the NixOS bootloader entries.
This key determines sorting relative to non-NixOS entries.
See also https://uapi-group.org/specifications/specs/boot_loader_specification/#sorting
This option can also be used to control the sorting of NixOS specialisations.
By default, specialisations inherit the sort key of their parent generation
and will have the same value for both the sort-key and the version (i.e. the generation number),
systemd-boot will therefore sort them based on their file name, meaning that
in your boot menu you will have each main generation directly followed by
its specialisations sorted alphabetically by their names.
If you want a different ordering for a specialisation, you can override
its sort-key which will cause the specialisation to be uncoupled from its
parent generation. It will then be sorted by its new sort-key just like
any other boot entry.
The sort-key is stored in the generation's bootspec, which means that
generations keep their sort-keys even if the original definition of the
generation was removed from the NixOS configuration.
It also means that updating the sort-key will only affect new generations,
while old ones will keep the sort-key that they were originally built with.
'';
};
editor = mkOption {
default = true;
@ -184,13 +223,15 @@ in {
'';
};
entryFilename = mkOption {
default = "memtest86.conf";
sortKey = mkOption {
default = "o_memtest86";
type = types.str;
description = lib.mdDoc ''
`systemd-boot` orders the menu entries by the config file names,
`systemd-boot` orders the menu entries by their sort keys,
so if you want something to appear after all the NixOS entries,
it should start with {file}`o` or onwards.
See also {option}`boot.loader.systemd-boot.sortKey`.
'';
};
};
@ -207,13 +248,15 @@ in {
'';
};
entryFilename = mkOption {
default = "o_netbootxyz.conf";
sortKey = mkOption {
default = "o_netbootxyz";
type = types.str;
description = lib.mdDoc ''
`systemd-boot` orders the menu entries by the config file names,
`systemd-boot` orders the menu entries by their sort keys,
so if you want something to appear after all the NixOS entries,
it should start with {file}`o` or onwards.
See also {option}`boot.loader.systemd-boot.sortKey`.
'';
};
};
@ -225,6 +268,7 @@ in {
{ "memtest86.conf" = '''
title Memtest86+
efi /efi/memtest86/memtest.efi
sort-key z_memtest
'''; }
'';
description = lib.mdDoc ''
@ -233,9 +277,10 @@ in {
Each attribute name denotes the destination file name,
and the corresponding attribute value is the contents of the entry.
`systemd-boot` orders the menu entries by the config file names,
so if you want something to appear after all the NixOS entries,
it should start with {file}`o` or onwards.
To control the ordering of the entry in the boot menu, use the sort-key
field, see
https://uapi-group.org/specifications/specs/boot_loader_specification/#sorting
and {option}`boot.loader.systemd-boot.sortKey`.
'';
};
@ -328,19 +373,25 @@ in {
boot.loader.systemd-boot.extraEntries = mkMerge [
(mkIf cfg.memtest86.enable {
"${cfg.memtest86.entryFilename}" = ''
"memtest86.conf" = ''
title Memtest86+
efi /efi/memtest86/memtest.efi
sort-key ${cfg.memtest86.sortKey}
'';
})
(mkIf cfg.netbootxyz.enable {
"${cfg.netbootxyz.entryFilename}" = ''
"netbootxyz.conf" = ''
title netboot.xyz
efi /efi/netbootxyz/netboot.xyz.efi
sort-key ${cfg.netbootxyz.sortKey}
'';
})
];
boot.bootspec.extensions."org.nixos.systemd-boot" = {
inherit (config.boot.loader.systemd-boot) sortKey;
};
system = {
build.installBootLoader = finalSystemdBootBuilder;

28
nixos/tests/systemd-boot.nix
View File

@ -93,6 +93,7 @@ in
machine.wait_for_unit("multi-user.target")
machine.succeed("test -e /boot/loader/entries/nixos-generation-1.conf")
machine.succeed("grep 'sort-key nixos' /boot/loader/entries/nixos-generation-1.conf")
# Ensure we actually booted using systemd-boot
# Magic number is the vendor UUID used by systemd-boot.
@ -164,7 +165,9 @@ in
nodes.machine = { pkgs, lib, ... }: {
imports = [ common ];
specialisation.something.configuration = {};
specialisation.something.configuration = {
boot.loader.systemd-boot.sortKey = "something";
};
};
testScript = ''
@ -177,6 +180,9 @@ in
machine.succeed(
"grep -q 'title NixOS (something)' /boot/loader/entries/nixos-generation-1-specialisation-something.conf"
)
machine.succeed(
"grep 'sort-key something' /boot/loader/entries/nixos-generation-1-specialisation-something.conf"
)
'';
};
@ -254,25 +260,25 @@ in
};
testScript = ''
machine.succeed("test -e /boot/loader/entries/o_netbootxyz.conf")
machine.succeed("test -e /boot/loader/entries/netbootxyz.conf")
machine.succeed("test -e /boot/efi/netbootxyz/netboot.xyz.efi")
'';
};
entryFilename = makeTest {
name = "systemd-boot-entry-filename";
memtestSortKey = makeTest {
name = "systemd-boot-memtest-sortkey";
meta.maintainers = with pkgs.lib.maintainers; [ Enzime julienmalka ];
nodes.machine = { pkgs, lib, ... }: {
imports = [ common ];
boot.loader.systemd-boot.memtest86.enable = true;
boot.loader.systemd-boot.memtest86.entryFilename = "apple.conf";
boot.loader.systemd-boot.memtest86.sortKey = "apple";
};
testScript = ''
machine.fail("test -e /boot/loader/entries/memtest86.conf")
machine.succeed("test -e /boot/loader/entries/apple.conf")
machine.succeed("test -e /boot/loader/entries/memtest86.conf")
machine.succeed("test -e /boot/efi/memtest86/memtest.efi")
machine.succeed("grep 'sort-key apple' /boot/loader/entries/memtest86.conf")
'';
};
@ -283,7 +289,6 @@ in
nodes.machine = { pkgs, lib, ... }: {
imports = [ commonXbootldr ];
boot.loader.systemd-boot.memtest86.enable = true;
boot.loader.systemd-boot.memtest86.entryFilename = "apple.conf";
};
testScript = { nodes, ... }: ''
@ -293,8 +298,7 @@ in
machine.wait_for_unit("multi-user.target")
machine.succeed("test -e /efi/EFI/systemd/systemd-bootx64.efi")
machine.fail("test -e /boot/loader/entries/memtest86.conf")
machine.succeed("test -e /boot/loader/entries/apple.conf")
machine.succeed("test -e /boot/loader/entries/memtest86.conf")
machine.succeed("test -e /boot/EFI/memtest86/memtest.efi")
'';
};
@ -386,9 +390,9 @@ in
machine.succeed("${finalSystem}/bin/switch-to-configuration boot")
machine.fail("test -e /boot/efi/fruits/tomato.efi")
machine.fail("test -e /boot/efi/nixos/.extra-files/efi/fruits/tomato.efi")
machine.succeed("test -e /boot/loader/entries/o_netbootxyz.conf")
machine.succeed("test -e /boot/loader/entries/netbootxyz.conf")
machine.succeed("test -e /boot/efi/netbootxyz/netboot.xyz.efi")
machine.succeed("test -e /boot/efi/nixos/.extra-files/loader/entries/o_netbootxyz.conf")
machine.succeed("test -e /boot/efi/nixos/.extra-files/loader/entries/netbootxyz.conf")
machine.succeed("test -e /boot/efi/nixos/.extra-files/efi/netbootxyz/netboot.xyz.efi")
'';
};