Unverified Commit fca8ee91 authored by Jared Baur's avatar Jared Baur
Browse files

nixos/systemd-boot: add support for devicetree entry 

The [Boot Loader Specification](https://uapi-group.org/specifications/specs/boot_loader_specification/)
allows for using a key called "devicetree" for specifying which
devicetree the bootloader should use during boot. With regards to
systemd-boot, this key is used to specify which file should be picked up
from the ESP to install to the EFI DTB Configuration Table. Linux then uses
this Configuration Table to setup the machine. This change is similar to
the one done in https://github.com/NixOS/nixpkgs/pull/295096, where that
change was for adding DTB support to systemd-stub, and this is for
systemd-boot.
parent 6614b28f

nixos/modules/system/boot/loader/systemd-boot/systemd-boot-builder.py

+12 −3
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ class BootSpec: 
    toplevel: str

    specialisations: dict[str, "BootSpec"]

    sortKey: str  # noqa: N815

    devicetree: str | None = None  # noqa: N815

    initrdSecrets: str | None = None  # noqa: N815



@dataclass
@@ -84,6 +85,7 @@ class DiskEntry: 
    kernel_params: str | None

    machine_id: str | None

    sort_key: str

    devicetree: str | None



    @classmethod

    def from_path(cls: Type["DiskEntry"], path: Path) -> "DiskEntry":
@@ -108,7 +110,9 @@ class DiskEntry: 
            initrd=entry_map["initrd"],

            kernel_params=entry_map.get("options"),

            machine_id=entry_map.get("machine-id"),

            sort_key=entry_map.get("sort_key", "nixos"))

            sort_key=entry_map.get("sort_key", "nixos"),

            devicetree=entry_map.get("devicetree"),

        )

        return disk_entry



    def write(self, sorted_first: str) -> None:
@@ -127,7 +131,8 @@ class DiskEntry: 
                f"initrd  {self.initrd}",

                f"options {self.kernel_params}" if self.kernel_params is not None else None,

                f"machine-id {self.machine_id}" if self.machine_id is not None else None,

                f"sort-key {default_sort_key if self.default else self.sort_key}"

                f"sort-key {default_sort_key if self.default else self.sort_key}",

                f"devicetree {self.devicetree}" if self.devicetree is not None else None,

            ]



            f.write("\n".join(filter(None, boot_entry)))
@@ -233,10 +238,12 @@ def bootspec_from_json(bootspec_json: dict[str, Any]) -> BootSpec: 
    specialisations = {k: bootspec_from_json(v) for k, v in specialisations.items()}

    systemdBootExtension = bootspec_json.get('org.nixos.systemd-boot', {})

    sortKey = systemdBootExtension.get('sortKey', 'nixos')

    devicetree = systemdBootExtension.get('devicetree')

    return BootSpec(

        **bootspec_json['org.nixos.bootspec.v1'],

        specialisations=specialisations,

        sortKey=sortKey

        sortKey=sortKey,

        devicetree=devicetree,

    )
@@ -261,6 +268,7 @@ def write_entry(profile: str | None, 
        bootspec = bootspec.specialisations[specialisation]

    kernel = copy_from_file(bootspec.kernel)

    initrd = copy_from_file(bootspec.initrd)

    devicetree = copy_from_file(bootspec.devicetree) if bootspec.devicetree is not None else None



    title = "{name}{profile}{specialisation}".format(

        name=DISTRO_NAME,
@@ -303,6 +311,7 @@ def write_entry(profile: str | None, 
        machine_id=machine_id,

        description=f"Generation {generation} {bootspec.label}, built on {build_date}",

        sort_key=bootspec.sortKey,

        devicetree=devicetree,

        default=current

    ).write(sorted_first)

nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix

+14 −0
Original line number Diff line number Diff line
@@ -191,6 +191,15 @@ in { 
      '';

    };



    installDeviceTree = mkOption {

      default = with config.hardware.deviceTree; enable && name != null;

      defaultText = ''with config.hardware.deviceTree; enable && name != null'';

      description = ''

        Install the devicetree blob specified by `config.hardware.deviceTree.name`

        to the ESP and instruct systemd-boot to pass this DTB to linux.

      '';

    };



    extraInstallCommands = mkOption {

      default = "";

      example = ''
@@ -353,6 +362,10 @@ in { 
        assertion = (config.boot.kernelPackages.kernel.features or { efiBootStub = true; }) ? efiBootStub;

        message = "This kernel does not support the EFI boot stub";

      }

      {

        assertion = cfg.installDeviceTree -> config.hardware.deviceTree.enable -> config.hardware.deviceTree.name != null;

        message = "Cannot install devicetree without 'config.hardware.deviceTree.enable' enabled and 'config.hardware.deviceTree.name' set";

      }

    ] ++ concatMap (filename: [

      {

        assertion = !(hasInfix "/" filename);
@@ -410,6 +423,7 @@ in { 


    boot.bootspec.extensions."org.nixos.systemd-boot" = {

      inherit (config.boot.loader.systemd-boot) sortKey;

      devicetree = lib.mkIf cfg.installDeviceTree "${config.hardware.deviceTree.package}/${config.hardware.deviceTree.name}";

    };



    system = {