nixos/systemd-boot: Add support for an XBOOTLDR partition

maintainers/maintainer-list.nix

@@ -16674,6 +16674,12 @@
     githubId = 7401858;
     name = "Sterling Stein";
   };
+  sdht0 = {
+    email = "[email protected]";
+    github = "sdht0";
+    githubId = 867424;
+    name = "Siddhartha Sahu";
+  };
   sdier = {
     email = "[email protected]";
     matrix = "@sdier:matrix.org";

nixos/doc/manual/release-notes/rl-2405.section.md

@@ -158,6 +158,10 @@ The pre-existing [services.ankisyncd](#opt-services.ankisyncd.enable) has been m
 
 - Cinnamon has been updated to 6.0. Please beware that the [Wayland session](https://blog.linuxmint.com/?p=4591) is still experimental in this release.
 
+- New `boot.loader.systemd-boot.xbootldrMountPoint` allows setting up a separate [XBOOTLDR partition](https://uapi-group.org/specifications/specs/boot_loader_specification/) to store boot files. Useful on systems with a small EFI System partition that cannot be easily repartitioned.
+
+- `boot.loader.systemd-boot` will now verify that `efiSysMountPoint` (and `xbootldrMountPoint` if configured) are mounted partitions.
+
 - `services.postgresql.extraPlugins` changed its type from just a list of packages to also a function that returns such a list.
   For example a config line like ``services.postgresql.extraPlugins = with pkgs.postgresql_11.pkgs; [ postgis ];`` is recommended to be changed to ``services.postgresql.extraPlugins = ps: with ps; [ postgis ];``;
 

nixos/lib/make-disk-image.nix

@@ -56,6 +56,14 @@ This partition table type uses GPT and:
 - creates an FAT32 ESP partition from 8MiB to specified `bootSize` parameter (256MiB by default), set it bootable ;
 - creates an primary ext4 partition starting after the boot partition and extending to the full disk image
 
+#### `efixbootldr`
+
+This partition table type uses GPT and:
+
+- creates an FAT32 ESP partition from 8MiB to 100MiB, set it bootable ;
+- creates an FAT32 BOOT partition from 100MiB to specified `bootSize` parameter (256MiB by default), set `bls_boot` flag ;
+- creates an primary ext4 partition starting after the boot partition and extending to the full disk image
+
 #### `hybrid`
 
 This partition table type uses GPT and:
@@ -111,19 +119,7 @@ To solve this, you can run `fdisk -l $image` and generate `dd if=$image of=$imag
   # When setting one of `user' or `group', the other needs to be set too.
   contents ? []
 
-, # Type of partition table to use; either "legacy", "efi", or "none".
-  # For "efi" images, the GPT partition table is used and a mandatory ESP
-  #   partition of reasonable size is created in addition to the root partition.
-  # For "legacy", the msdos partition table is used and a single large root
-  #   partition is created.
-  # For "legacy+gpt", the GPT partition table is used, a 1MiB no-fs partition for
-  #   use by the bootloader is created, and a single large root partition is
-  #   created.
-  # For "hybrid", the GPT partition table is used and a mandatory ESP
-  #   partition of reasonable size is created in addition to the root partition.
-  #   Also a legacy MBR will be present.
-  # For "none", no partition table is created. Enabling `installBootLoader`
-  #   most likely fails as GRUB will probably refuse to install.
+, # Type of partition table to use; described in the `Image Partitioning` section above.
   partitionTableType ? "legacy"
 
 , # Whether to invoke `switch-to-configuration boot` during image creation
@@ -193,11 +189,11 @@ To solve this, you can run `fdisk -l $image` and generate `dd if=$image of=$imag
   additionalPaths ? []
 }:
 
-assert (lib.assertOneOf "partitionTableType" partitionTableType [ "legacy" "legacy+gpt" "efi" "hybrid" "none" ]);
+assert (lib.assertOneOf "partitionTableType" partitionTableType [ "legacy" "legacy+gpt" "efi" "efixbootldr" "hybrid" "none" ]);
 assert (lib.assertMsg (fsType == "ext4" && deterministic -> rootFSUID != null) "In deterministic mode with a ext4 partition, rootFSUID must be non-null, by default, it is equal to rootGPUID.");
   # We use -E offset=X below, which is only supported by e2fsprogs
 assert (lib.assertMsg (partitionTableType != "none" -> fsType == "ext4") "to produce a partition table, we need to use -E offset flag which is support only for fsType = ext4");
-assert (lib.assertMsg (touchEFIVars -> partitionTableType == "hybrid" || partitionTableType == "efi" || partitionTableType == "legacy+gpt") "EFI variables can be used only with a partition table of type: hybrid, efi or legacy+gpt.");
+assert (lib.assertMsg (touchEFIVars -> partitionTableType == "hybrid" || partitionTableType == "efi" || partitionTableType == "efixbootldr" || partitionTableType == "legacy+gpt") "EFI variables can be used only with a partition table of type: hybrid, efi, efixbootldr, or legacy+gpt.");
   # If only Nix store image, then: contents must be empty, configFile must be unset, and we should no install bootloader.
 assert (lib.assertMsg (onlyNixStore -> contents == [] && configFile == null && !installBootLoader) "In a only Nix store image, the contents must be empty, no configuration must be provided and no bootloader should be installed.");
 # Either both or none of {user,group} need to be set
@@ -225,6 +221,7 @@ let format' = format; in let
     legacy = "1";
     "legacy+gpt" = "2";
     efi = "2";
+    efixbootldr = "3";
     hybrid = "3";
   }.${partitionTableType};
 
@@ -266,6 +263,23 @@ let format' = format; in let
           $diskImage
       ''}
     '';
+    efixbootldr = ''
+      parted --script $diskImage -- \
+        mklabel gpt \
+        mkpart ESP fat32 8MiB 100MiB \
+        set 1 boot on \
+        mkpart BOOT fat32 100MiB ${bootSize} \
+        set 2 bls_boot on \
+        mkpart ROOT ext4 ${bootSize} -1
+      ${optionalString deterministic ''
+          sgdisk \
+          --disk-guid=97FD5997-D90B-4AA3-8D16-C1723AEA73C \
+          --partition-guid=1:1C06F03B-704E-4657-B9CD-681A087A2FDC  \
+          --partition-guid=2:970C694F-AFD0-4B99-B750-CDB7A329AB6F  \
+          --partition-guid=3:${rootGPUID} \
+          $diskImage
+      ''}
+    '';
     hybrid = ''
       parted --script $diskImage -- \
         mklabel gpt \
@@ -436,7 +450,7 @@ let format' = format; in let
     diskImage=nixos.raw
 
     ${if diskSize == "auto" then ''
-      ${if partitionTableType == "efi" || partitionTableType == "hybrid" then ''
+      ${if partitionTableType == "efi" || partitionTableType == "efixbootldr" || partitionTableType == "hybrid" then ''
         # Add the GPT at the end
         gptSpace=$(( 512 * 34 * 1 ))
         # Normally we'd need to account for alignment and things, if bootSize
@@ -567,6 +581,15 @@ let format' = format; in let
 
         ${optionalString touchEFIVars "mount -t efivarfs efivarfs /sys/firmware/efi/efivars"}
       ''}
+      ${optionalString (partitionTableType == "efixbootldr") ''
+        mkdir -p /mnt/{boot,efi}
+        mkfs.vfat -n ESP /dev/vda1
+        mkfs.vfat -n BOOT /dev/vda2
+        mount /dev/vda1 /mnt/efi
+        mount /dev/vda2 /mnt/boot
+
+        ${optionalString touchEFIVars "mount -t efivarfs efivarfs /sys/firmware/efi/efivars"}
+      ''}
 
       # Install a configuration.nix
       mkdir -p /mnt/etc/nixos

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

@@ -17,6 +17,9 @@
 
 # These values will be replaced with actual values during the package build
 EFI_SYS_MOUNT_POINT = "@efiSysMountPoint@"
+BOOT_MOUNT_POINT = "@bootMountPoint@"
+LOADER_CONF = f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf"  # Always stored on the ESP
+NIXOS_DIR = "@nixosDir@"
 TIMEOUT = "@timeout@"
 EDITOR = bool("@editor@")
 CONSOLE_MODE = "@consoleMode@"
@@ -28,6 +31,7 @@
 CAN_TOUCH_EFI_VARIABLES = "@canTouchEfiVariables@"
 GRACEFUL = "@graceful@"
 COPY_EXTRA_FILES = "@copyExtraFiles@"
+CHECK_MOUNTPOINTS = "@checkMountpoints@"
 
 @dataclass
 class BootSpec:
@@ -87,7 +91,7 @@ def generation_conf_filename(profile: str | None, generation: int, specialisatio
 
 
 def write_loader_conf(profile: str | None, generation: int, specialisation: str | None) -> None:
-    with open(f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf.tmp", 'w') as f:
+    with open(f"{LOADER_CONF}.tmp", 'w') as f:
         if TIMEOUT != "":
             f.write(f"timeout {TIMEOUT}\n")
         f.write("default %s\n" % generation_conf_filename(profile, generation, specialisation))
@@ -96,7 +100,7 @@ def write_loader_conf(profile: str | None, generation: int, specialisation: str
         f.write(f"console-mode {CONSOLE_MODE}\n")
         f.flush()
         os.fsync(f.fileno())
-    os.rename(f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf.tmp", f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf")
+    os.rename(f"{LOADER_CONF}.tmp", LOADER_CONF)
 
 
 def get_bootspec(profile: str | None, generation: int) -> BootSpec:
@@ -126,9 +130,9 @@ def copy_from_file(file: str, dry_run: bool = False) -> str:
     store_file_path = os.path.realpath(file)
     suffix = os.path.basename(store_file_path)
     store_dir = os.path.basename(os.path.dirname(store_file_path))
-    efi_file_path = "/efi/nixos/%s-%s.efi" % (store_dir, suffix)
+    efi_file_path = f"{NIXOS_DIR}/{store_dir}-{suffix}.efi"
     if not dry_run:
-        copy_if_not_exists(store_file_path, f"{EFI_SYS_MOUNT_POINT}%s" % (efi_file_path))
+        copy_if_not_exists(store_file_path, f"{BOOT_MOUNT_POINT}{efi_file_path}")
     return efi_file_path
 
 def write_entry(profile: str | None, generation: int, specialisation: str | None,
@@ -145,7 +149,7 @@ def write_entry(profile: str | None, generation: int, specialisation: str | None
 
     try:
         if bootspec.initrdSecrets is not None:
-            subprocess.check_call([bootspec.initrdSecrets, f"{EFI_SYS_MOUNT_POINT}%s" % (initrd)])
+            subprocess.check_call([bootspec.initrdSecrets, f"{BOOT_MOUNT_POINT}%s" % (initrd)])
     except subprocess.CalledProcessError:
         if current:
             print("failed to create initrd secrets!", file=sys.stderr)
@@ -155,7 +159,7 @@ def write_entry(profile: str | None, generation: int, specialisation: str | None
                   f'for "{title} - Configuration {generation}", an older generation', file=sys.stderr)
             print("note: this is normal after having removed "
                   "or renamed a file in `boot.initrd.secrets`", file=sys.stderr)
-    entry_file = f"{EFI_SYS_MOUNT_POINT}/loader/entries/%s" % (
+    entry_file = f"{BOOT_MOUNT_POINT}/loader/entries/%s" % (
         generation_conf_filename(profile, generation, specialisation))
     tmp_path = "%s.tmp" % (entry_file)
     kernel_params = "init=%s " % bootspec.init
@@ -202,14 +206,14 @@ def get_generations(profile: str | None = None) -> list[SystemIdentifier]:
 
 
 def remove_old_entries(gens: list[SystemIdentifier]) -> None:
-    rex_profile = re.compile(r"^" + re.escape(EFI_SYS_MOUNT_POINT) + "/loader/entries/nixos-(.*)-generation-.*\.conf$")
-    rex_generation = re.compile(r"^" + re.escape(EFI_SYS_MOUNT_POINT) + "/loader/entries/nixos.*-generation-([0-9]+)(-specialisation-.*)?\.conf$")
+    rex_profile = re.compile(r"^" + re.escape(BOOT_MOUNT_POINT) + "/loader/entries/nixos-(.*)-generation-.*\.conf$")
+    rex_generation = re.compile(r"^" + re.escape(BOOT_MOUNT_POINT) + "/loader/entries/nixos.*-generation-([0-9]+)(-specialisation-.*)?\.conf$")
     known_paths = []
     for gen in gens:
         bootspec = get_bootspec(gen.profile, gen.generation)
         known_paths.append(copy_from_file(bootspec.kernel, True))
         known_paths.append(copy_from_file(bootspec.initrd, True))
-    for path in glob.iglob(f"{EFI_SYS_MOUNT_POINT}/loader/entries/nixos*-generation-[1-9]*.conf"):
+    for path in glob.iglob(f"{BOOT_MOUNT_POINT}/loader/entries/nixos*-generation-[1-9]*.conf"):
         if rex_profile.match(path):
             prof = rex_profile.sub(r"\1", path)
         else:
@@ -220,11 +224,18 @@ def remove_old_entries(gens: list[SystemIdentifier]) -> None:
             continue
         if not (prof, gen_number, None) in gens:
             os.unlink(path)
-    for path in glob.iglob(f"{EFI_SYS_MOUNT_POINT}/efi/nixos/*"):
+    for path in glob.iglob(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/*"):
         if not path in known_paths and not os.path.isdir(path):
             os.unlink(path)
 
 
+def cleanup_esp() -> None:
+    for path in glob.iglob(f"{EFI_SYS_MOUNT_POINT}/loader/entries/nixos*"):
+        os.unlink(path)
+    if os.path.isdir(f"{EFI_SYS_MOUNT_POINT}/{NIXOS_DIR}"):
+        shutil.rmtree(f"{EFI_SYS_MOUNT_POINT}/{NIXOS_DIR}")
+
+
 def get_profiles() -> list[str]:
     if os.path.isdir("/nix/var/nix/profiles/system-profiles/"):
         return [x
@@ -255,6 +266,9 @@ def install_bootloader(args: argparse.Namespace) -> None:
     # flags to pass to bootctl install/update
     bootctl_flags = []
 
+    if BOOT_MOUNT_POINT != EFI_SYS_MOUNT_POINT:
+        bootctl_flags.append(f"--boot-path={BOOT_MOUNT_POINT}")
+
     if CAN_TOUCH_EFI_VARIABLES != "1":
         bootctl_flags.append("--no-variables")
 
@@ -263,8 +277,8 @@ def install_bootloader(args: argparse.Namespace) -> None:
 
     if os.getenv("NIXOS_INSTALL_BOOTLOADER") == "1":
         # bootctl uses fopen() with modes "wxe" and fails if the file exists.
-        if os.path.exists(f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf"):
-            os.unlink(f"{EFI_SYS_MOUNT_POINT}/loader/loader.conf")
+        if os.path.exists(LOADER_CONF):
+            os.unlink(LOADER_CONF)
 
         subprocess.check_call([f"{SYSTEMD}/bin/bootctl", f"--esp-path={EFI_SYS_MOUNT_POINT}"] + bootctl_flags + ["install"])
     else:
@@ -291,13 +305,15 @@ def install_bootloader(args: argparse.Namespace) -> None:
             print("updating systemd-boot from %s to %s" % (installed_version, available_version))
             subprocess.check_call([f"{SYSTEMD}/bin/bootctl", f"--esp-path={EFI_SYS_MOUNT_POINT}"] + bootctl_flags + ["update"])
 
-    os.makedirs(f"{EFI_SYS_MOUNT_POINT}/efi/nixos", exist_ok=True)
-    os.makedirs(f"{EFI_SYS_MOUNT_POINT}/loader/entries", exist_ok=True)
+    os.makedirs(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}", exist_ok=True)
+    os.makedirs(f"{BOOT_MOUNT_POINT}/loader/entries", exist_ok=True)
 
     gens = get_generations()
     for profile in get_profiles():
         gens += get_generations(profile)
+
     remove_old_entries(gens)
+
     for gen in gens:
         try:
             bootspec = get_bootspec(gen.profile, gen.generation)
@@ -315,9 +331,15 @@ def install_bootloader(args: argparse.Namespace) -> None:
             else:
                 raise e
 
-    for root, _, files in os.walk(f"{EFI_SYS_MOUNT_POINT}/efi/nixos/.extra-files", topdown=False):
-        relative_root = root.removeprefix(f"{EFI_SYS_MOUNT_POINT}/efi/nixos/.extra-files").removeprefix("/")
-        actual_root = os.path.join(f"{EFI_SYS_MOUNT_POINT}", relative_root)
+    if BOOT_MOUNT_POINT != EFI_SYS_MOUNT_POINT:
+        # Cleanup any entries in ESP if xbootldrMountPoint is set.
+        # If the user later unsets xbootldrMountPoint, entries in XBOOTLDR will not be cleaned up
+        # automatically, as we don't have information about the mount point anymore.
+        cleanup_esp()
+
+    for root, _, files in os.walk(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/.extra-files", topdown=False):
+        relative_root = root.removeprefix(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/.extra-files").removeprefix("/")
+        actual_root = os.path.join(f"{BOOT_MOUNT_POINT}", relative_root)
 
         for file in files:
             actual_file = os.path.join(actual_root, file)
@@ -330,7 +352,7 @@ def install_bootloader(args: argparse.Namespace) -> None:
             os.rmdir(actual_root)
         os.rmdir(root)
 
-    os.makedirs(f"{EFI_SYS_MOUNT_POINT}/efi/nixos/.extra-files", exist_ok=True)
+    os.makedirs(f"{BOOT_MOUNT_POINT}/{NIXOS_DIR}/.extra-files", exist_ok=True)
 
     subprocess.check_call(COPY_EXTRA_FILES)
 
@@ -340,16 +362,23 @@ def main() -> None:
     parser.add_argument('default_config', metavar='DEFAULT-CONFIG', help=f"The default {DISTRO_NAME} config to boot")
     args = parser.parse_args()
 
+    subprocess.check_call(CHECK_MOUNTPOINTS)
+
     try:
         install_bootloader(args)
     finally:
         # Since fat32 provides little recovery facilities after a crash,
         # it can leave the system in an unbootable state, when a crash/outage
         # happens shortly after an update. To decrease the likelihood of this
         # event sync the efi filesystem after each update.
-        rc = libc.syncfs(os.open(f"{EFI_SYS_MOUNT_POINT}", os.O_RDONLY))
+        rc = libc.syncfs(os.open(f"{BOOT_MOUNT_POINT}", os.O_RDONLY))
         if rc != 0:
-            print(f"could not sync {EFI_SYS_MOUNT_POINT}: {os.strerror(rc)}", file=sys.stderr)
+            print(f"could not sync {BOOT_MOUNT_POINT}: {os.strerror(rc)}", file=sys.stderr)
+
+        if BOOT_MOUNT_POINT != EFI_SYS_MOUNT_POINT:
+            rc = libc.syncfs(os.open(EFI_SYS_MOUNT_POINT, os.O_RDONLY))
+            if rc != 0:
+                print(f"could not sync {EFI_SYS_MOUNT_POINT}: {os.strerror(rc)}", file=sys.stderr)
 
 
 if __name__ == '__main__':