wic: add --extra-partition-space option to set unused space

By default, the content of the partition is filled by the filesystem
without leaving any unused free space. The --extra-space flag adds
extra space to the filesystem size, not to the partition.

Unused free space after the filesystem can be useful for some cases,
such as encrypting a partition at runtime.
With --extra-partition-space 32M, we ensure that the last 32M of the
partition is unused: this space does not contain filesystem data and
can store the LUKS2 header.

The implementation sets a difference between the partition and
filesystem size:
  - With --fixed-size, the extra part space is removed from the
    filesystem size.
  - Otherwise (with or without --size flag), the extra part space is
    added to the partition size.

(From OE-Core rev: 22fd1702aedf40257aa53963b62b5ef1bbd2818a)

Signed-off-by: Pierre-Loup GOSSE <pierre-loup.gosse@smile.fr>

CC: Alexander Kanavin <alex.kanavin@gmail.com>
CC: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 3 insertions, 0 deletions

diff --git a/scripts/lib/wic/ksparser.py b/scripts/lib/wic/ksparser.py
index 596b6e8e7e..a1aaf1b4b3 100644
--- a/scripts/lib/wic/ksparser.py
+++ b/scripts/lib/wic/ksparser.py
@@ -154,6 +154,7 @@ class KickStart():
         part.add_argument('--include-path', nargs='+', action='append')
         part.add_argument('--change-directory')
         part.add_argument("--extra-space", type=sizetype("M"))
+        part.add_argument('--extra-partition-space', type=sizetype("M"))
         part.add_argument('--fsoptions', dest='fsopts')
         part.add_argument('--fspassno', dest='fspassno')
         part.add_argument('--fstype', default='vfat',
@@ -259,6 +260,8 @@ class KickStart():
                             err = "%s:%d: Must set the label with --label" \
                                   % (confpath, lineno)
                             raise KickStartError(err)
+                        if not parsed.extra_partition_space:
+                            parsed.extra_partition_space = 0
                         # using ArgumentParser one cannot easily tell if option
                         # was passed as argument, if said option has a default
                         # value; --overhead-factor/--extra-space cannot be used