Move OEM mount point out of /usr

[pothos]

Current situation

The OEM partition is mounted under /usr/share/oem/ which requires a workaround for systemd-sysext because the management of the overlay mounts on /usr results in the OEM mount point to be lost without the workaround.

Impact

We had to add a special handling for the OEM mount point in the systemd-sysext service. Users manually invoking systemd-sysext will lose the partition mount - while we don't support manual usage of the CLI command for the reason that it doesn't reload and start new services, this is a lesser evil than a broken system because of the OEM partition being inaccessible.

Ideal future situation

We can drop the special handling because the OEM partition is mounted elsewhere, e.g., under /oem/ and a symlink from /usr/share/oem/ exists for backwards compatibility.

Implementation options

Additional information

/usr/lib/systemd/system/systemd-sysext.service.d/10-mount-oem-partition.conf is the workaround

[pothos]

Since we also mount the OEM partition from the initrd under /sysroot, something like /oem would be a good new mountpoint.

[krnowak]

Since we also mount the OEM partition from the initrd under /sysroot, something like /oem would be a good new mountpoint.

Yeah, that's what I'm using.