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If the *.wks file contains a "--source rootfs" then
lib/wic/plugins/source/rootfs.py will be invoked to generate (what is assumed
to be) the rootfs partition. If the rootfs partition needs to be tweaked or
modified, the "rootfs.py" plugin will make a copy of the filesystem and then
perform the changes on that copy. In other words, if the "--source rootfs"
line of the *.wks file also contains any of:
--exclude-path
--include-path
--change-directory
--use-label (i.e. modify etc/fstab)
then the rootfs will be copied first, then the copy is modified.
If, for example, the unmodified IMAGE_ROOTFS is:
.../tmp/work/qemuarm64_secureboot-oe-linux/core-image-base/1.0/rootfs
then the copy would be made at:
.../tmp/work/qemuarm64_secureboot-oe-linux/core-image-base/1.0/tmp-wic/rootfs${LINENO}
where ${LINENO} is the line number where this "--source rootfs" line appears
in the *wks file.
When it comes time to make an actual partition of a specific filesystem type,
lib/wic/partition.py::prepare_rootfs() is called. It is in this function that
wic figures out if any extra size needs to be added. The bitbake variable used
to specify the ultimate rootfs size is ROOTFS_SIZE, and since this variable is
only valid for the rootfs (and not any other partitions), the code also
verifies that the partition being created is ${IMAGE_ROOTFS}:
rsize_bb = get_bitbake_var('ROOTFS_SIZE')
rdir = get_bitbake_var('IMAGE_ROOTFS')
if rsize_bb and rdir == rootfs_dir:
<use rsize_bb>
else:
<calculate the partition size using "du -ks $p">
As noted above, if lib/wic/plugins/source/rootfs.py has made a copy, then the
"rdir == rootfs_dir" clause will fail and the code will assume this partition
is not a rootfs since the strings do not compare equal.
Therefore, in order to determine if this is a rootfs, retain the existing
"rdir == rootfs_dir" comparison, but also add another one to check whether or
not this is a wic-generated copy of the rootfs.
STEPS TO REPRODUCE:
- start with the following *wks file:
bootloader --ptable gpt
part /boot --size=100M --active --fstype=ext4 --label boot
part / --source rootfs --fstype=ext4 --label root
- and the following extra variable in conf/local.conf:
IMAGE_ROOTFS_EXTRA_SPACE = "500000"
- build an image
- run it in qemu
$ runqemu slirp nographic serial
- verify the root partition has extra space:
root@qemuarm64-secureboot:~# df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 721.5M 67.4M 600.6M 10% /
devtmpfs 477.7M 0 477.7M 0% /dev
tmpfs 40.0K 0 40.0K 0% /mnt
tmpfs 489.3M 92.0K 489.2M 0% /run
tmpfs 489.3M 68.0K 489.2M 0% /var/volatile
/dev/vda1 120.4M 19.9M 91.4M 18% /boot
- modify the "/" line of the *wks file to be:
part / --source rootfs --fstype=ext4 --label root --exclude-path boot/
- build image
when it fails:
root@qemuarm64-secureboot:~# df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 73.4M 41.9M 25.8M 62% /
devtmpfs 477.7M 0 477.7M 0% /dev
tmpfs 40.0K 0 40.0K 0% /mnt
tmpfs 489.3M 92.0K 489.2M 0% /run
tmpfs 489.3M 68.0K 489.2M 0% /var/volatile
/dev/vda1 120.4M 19.9M 91.4M 18% /boot
after this fix:
root@qemuarm64-secureboot:~# df -h
Filesystem Size Used Available Use% Mounted on
/dev/root 721.5M 47.4M 620.6M 7% /
devtmpfs 477.7M 0 477.7M 0% /dev
tmpfs 40.0K 0 40.0K 0% /mnt
tmpfs 489.3M 92.0K 489.2M 0% /run
tmpfs 489.3M 68.0K 489.2M 0% /var/volatile
/dev/vda1 120.4M 19.9M 91.4M 18% /boot
Doing the math we see that the /boot partition is ~20MB and in the first image
the / partition contains this ~20MB in addition to the rest of the rootfs.
This ~20MB is completely wasted since it is used in the / partition, but then
the /boot partition is mounted on top of it, making the /boot directory of /
inaccessible. After the fix the / partition has an additional ~20MB since the
/boot portion is excluded.
Fixes [YOCTO #15555]
(From OE-Core rev: 1c690aa046ebca13d7b29de50d42b5d8a4a8486c)
Signed-off-by: Trevor Woerner <twoerner@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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|---|---|---|
| .. | ||
| build_perf | ||
| checklayer | ||
| devtool | ||
| recipetool | ||
| resulttool | ||
| wic | ||
| argparse_oe.py | ||
| buildstats.py | ||
| scriptpath.py | ||
| scriptutils.py | ||