pmbootstrap install: add --ondev --no-rootfs (MR 1995)

Skip building the postmarketOS rootfs, and allow either installing a
pre-built pmOS rootfs, or even another operating system.

pmb/helpers/frontend.py

@@ -70,6 +70,24 @@ def _parse_suffix(args):
         return "native"
 
 
+def _install_ondev_verify_no_rootfs(args):
+    chroot_dest = "/var/lib/rootfs.img"
+    dest = f"{args.work}/chroot_installer_{args.device}{chroot_dest}"
+    if os.path.exists(dest):
+        return
+
+    if args.ondev_cp:
+        for _, chroot_dest_cp in args.ondev_cp:
+            if chroot_dest_cp == chroot_dest:
+                return
+
+    raise ValueError(f"--no-rootfs set, but rootfs.img not found in install"
+                     " chroot. Either run 'pmbootstrap install' without"
+                     " --no-rootfs first to let it generate the postmarketOS"
+                     " rootfs once, or supply a rootfs file with:"
+                     f" --cp os.img:{chroot_dest}")
+
+
 def aportgen(args):
     for package in args.packages:
         logging.info("Generate aport: " + package)
@@ -236,6 +254,11 @@ def install(args):
     else:
         if args.ondev_cp:
             raise ValueError("--cp can only be combined with --ondev")
+        if args.ondev_no_rootfs:
+            raise ValueError("--no-rootfs can only be combined with --ondev."
+                             " Do you mean --no-image?")
+    if args.ondev_no_rootfs:
+        _install_ondev_verify_no_rootfs(args)
 
     # On-device installer overrides
     if args.on_device_installer:

pmb/install/_install.py

@@ -608,10 +608,11 @@ def install_recovery_zip(args, steps):
 
 def install_on_device_installer(args, step, steps):
     # Generate the rootfs image
-    suffix_rootfs = f"rootfs_{args.device}"
+    if not args.ondev_no_rootfs:
-    install_system_image(args, 0, suffix_rootfs, step=step, steps=steps,
+        suffix_rootfs = f"rootfs_{args.device}"
-                         split=True)
+        install_system_image(args, 0, suffix_rootfs, step=step, steps=steps,
-    step += 2
+                             split=True)
+        step += 2
 
     # Prepare the installer chroot
     logging.info(f"*** ({step}/{steps}) CREATE ON-DEVICE INSTALLER ROOTFS ***")
@@ -624,12 +625,13 @@ def install_on_device_installer(args, step, steps):
     pmb.chroot.apk.install(args, packages, suffix_installer)
 
     # Move rootfs image into installer chroot
-    img = f"{args.device}-root.img"
-    img_path_src = f"{args.work}/chroot_native/home/pmos/rootfs/{img}"
     img_path_dest = f"{args.work}/chroot_{suffix_installer}/var/lib/rootfs.img"
-    logging.info(f"({suffix_installer}) add {img} as /var/lib/rootfs.img")
+    if not args.ondev_no_rootfs:
-    pmb.install.losetup.umount(args, img_path_src)
+        img = f"{args.device}-root.img"
-    pmb.helpers.run.root(args, ["mv", img_path_src, img_path_dest])
+        img_path_src = f"{args.work}/chroot_native/home/pmos/rootfs/{img}"
+        logging.info(f"({suffix_installer}) add {img} as /var/lib/rootfs.img")
+        pmb.install.losetup.umount(args, img_path_src)
+        pmb.helpers.run.root(args, ["mv", img_path_src, img_path_dest])
 
     # Run ondev-prepare, so it may generate nice configs from the channel
     # properties (e.g. to display the version number), or transform the image
@@ -659,9 +661,10 @@ def install_on_device_installer(args, step, steps):
 
     # Remove $DEVICE-boot.img (we will generate a new one if --split was
     # specified, otherwise the separate boot image is not needed)
-    img_boot = f"{args.device}-boot.img"
+    if not args.ondev_no_rootfs:
-    logging.info(f"(native) rm {img_boot}")
+        img_boot = f"{args.device}-boot.img"
-    pmb.chroot.root(args, ["rm", f"/home/pmos/rootfs/{img_boot}"])
+        logging.info(f"(native) rm {img_boot}")
+        pmb.chroot.root(args, ["rm", f"/home/pmos/rootfs/{img_boot}"])
 
     # Generate installer image
     size_reserve = round(os.path.getsize(img_path_dest) / 1024 / 1024) + 200
@@ -740,7 +743,7 @@ def install(args):
     elif args.android_recovery_zip:
         steps = 3
     elif args.on_device_installer:
-        steps = 7
+        steps = 4 if args.ondev_no_rootfs else 7
     else:
         steps = 4
 
@@ -751,8 +754,9 @@ def install(args):
                            build=False)
     step += 1
 
-    create_device_rootfs(args, step, steps)
+    if not args.ondev_no_rootfs:
-    step += 1
+        create_device_rootfs(args, step, steps)
+        step += 1
 
     if args.no_image:
         return

pmb/parse/arguments.py

@@ -144,6 +144,12 @@ def arguments_install(subparser):
                        metavar="HOST_SRC:CHROOT_DEST", type=type_ondev_cp,
                        help="copy one or more files from the host system path"
                             " HOST_SRC to the target path CHROOT_DEST")
+    group.add_argument("--no-rootfs", dest="ondev_no_rootfs",
+                       help="do not generate a pmOS rootfs as"
+                            " /var/lib/rootfs.img (install chroot). The file"
+                            " must either exist from a previous"
+                            " 'pmbootstrap install' run or by providing it"
+                            " as CHROOT_DEST with --cp", action="store_true")
 
 
 def arguments_export(subparser):