Replace root=PARTUUID and mount.usr=PARTUUID with the actual partition UUID

These are not known upfront so let's treat these literals as placeholders
which are to be replaced with the actual partition UUID when we know it.

diff --git a/mkosi/__init__.py b/mkosi/__init__.py
index 474542c0869ab49722683006d18a41bccd6f835d..c88206156f44baf51c36c187f513434ebf60e775 100644 (file)
--- a/mkosi/__init__.py
+++ b/mkosi/__init__.py
@@ -2278,7 +2278,7 @@ def find_entry_token(context: Context) -> str:
     return cast(str, output["EntryToken"])
 
 
-def finalize_cmdline(context: Context, roothash: Optional[str]) -> list[str]:
+def finalize_cmdline(context: Context, partitions: Sequence[Partition], roothash: Optional[str]) -> list[str]:
     if (context.root / "etc/kernel/cmdline").exists():
         cmdline = [(context.root / "etc/kernel/cmdline").read_text().strip()]
     elif (context.root / "usr/lib/kernel/cmdline").exists():
@@ -2289,7 +2289,16 @@ def finalize_cmdline(context: Context, roothash: Optional[str]) -> list[str]:
     if roothash:
         cmdline += [roothash]
 
-    return cmdline + context.config.kernel_command_line
+    cmdline += context.config.kernel_command_line
+
+    if not roothash:
+        for name in ("root", "mount.usr"):
+            if not (root := next((p.uuid for p in partitions if p.type.startswith(name)), None)):
+                continue
+
+            cmdline = [f"{name}=PARTUUID={root}" if c == f"{name}=PARTUUID" else c for c in cmdline]
+
+    return cmdline
 
 
 def finalize_microcode(context: Context) -> list[Path]:
@@ -2322,7 +2331,7 @@ def install_type1(
         entry.parent.mkdir(parents=True, exist_ok=True)
 
     kmods = build_kernel_modules_initrd(context, kver)
-    cmdline = finalize_cmdline(context, finalize_roothash(partitions))
+    cmdline = finalize_cmdline(context, partitions, finalize_roothash(partitions))
 
     with umask(~0o600):
         if (
@@ -2360,8 +2369,12 @@ def install_type1(
         config = prepare_grub_config(context)
         assert config
 
-        root = finalize_root(partitions)
-        assert root
+        if (
+            not any(c.startswith("root=PARTUUID=") for c in context.config.kernel_command_line) and
+            not any(c.startswith("mount.usr=PARTUUID=") for c in context.config.kernel_command_line) and
+            (root := finalize_root(partitions))
+        ):
+            cmdline = [root] + cmdline
 
         with config.open("a") as f:
             f.write("if ")
@@ -2379,7 +2392,7 @@ def install_type1(
                 textwrap.dedent(
                     f"""\
                     menuentry "{token}-{kver}" {{
-                        linux /{kimg.relative_to(context.root / "boot")} {root} {" ".join(cmdline)}
+                        linux /{kimg.relative_to(context.root / "boot")} {" ".join(cmdline)}
                         initrd {" ".join(os.fspath(Path("/") / i.relative_to(context.root / "boot")) for i in initrds)}
                     }}
                     """
@@ -2470,7 +2483,7 @@ def install_uki(context: Context, kver: str, kimg: Path, token: str, partitions:
             context.root / kimg,
             microcodes,
             initrds,
-            finalize_cmdline(context, roothash),
+            finalize_cmdline(context, partitions, roothash),
             boot_binary,
         )
 

diff --git a/mkosi/resources/mkosi.md b/mkosi/resources/mkosi.md
index aa206bd3b90221652ef0a4fa11e06ccc133aba23..8ccbfa284918396ffab932cc4400a54721b04a98 100644 (file)
--- a/mkosi/resources/mkosi.md
+++ b/mkosi/resources/mkosi.md
@@ -1066,6 +1066,14 @@ boolean argument: either `1`, `yes`, or `true` to enable, or `0`, `no`,
 `KernelCommandLine=`, `--kernel-command-line=`
 :   Use the specified kernel command line when building images.
 
+    If the value of this setting contains the literals `root=PARTUUID`
+    or `mount.usr=PARTUUID`, these are replaced with the partition UUID
+    of the root or usr partition respectively. For example,
+    `root=PARTUUID` would be replaced with
+    `root=PARTUUID=58c7d0b2-d224-4834-a16f-e036322e88f7` where
+    `58c7d0b2-d224-4834-a16f-e036322e88f7` is the partition UUID of the
+    root partition.
+
 `KernelModulesInclude=`, `--kernel-modules-include=`
 :   Takes a list of regex patterns that specify kernel modules to include in the image. Patterns should be
     relative to the `/usr/lib/modules/<kver>/kernel` directory. mkosi checks for a match anywhere in the module