Re: execute pkg_postinst_ontarget when read-only-rootfs-delayed-postinsts is set for a read only rootfs

Hi Alex,

I looked into overlayfs.py but I'm not convinced that this is the right path. First of all, basically all relevant tests that could be used as a starting point use systemd as well which doesn't make them more generic compared to my test in runtime_test.py. Secondly, when I set IMAGE_FEATURES += "read-only-rootfs" in the test_correct_image_fstab test case, qemu also hangs during boot.

Again, I build a poky with the same configuration as the test case and got the following log messages during boot:

[FAILED] Failed to mount /mnt/overlay.
See 'systemctl status mnt-overlay.mount' for details.
[DEPEND] Dependency failed for Local File Systems.
[DEPEND] Dependency failed for Overlayfs directories setup.
[DEPEND] Dependency failed for Overlayfs mount unit.
[DEPEND] Dependency failed for Overlayfs directories setup.
[DEPEND] Dependency failed for Overlayfs mount unit.

and it start hanging at the following line:

You are in emergency mode. After logging in, type "journalctl -xb" to view
system logs, "systemctl reboot" to reboot, or "exit"
to continue bootup.
Press Enter for maintenance
(or press Control-D to continue):

when I enter systemctl status mnt-overlay.mount , I get:

Jul 05 13:49:39 qemux86-64 mount[138]: mount: /mnt/overlay: mount point does not exist.

/mnt/overlay is the mount point that is configured by the test. When I make the rootfs read only, the mount point can not be created and I get the error message. For a test, I changed the mount point to /tmp (which is writable even for a read-only rootfs), with that change, the system boots and the test passes.

Overall, I would say that such a kind of test is even worse and in no way more generic than my previous test implementation in runtime_test.py. What do you think?