Cannot create cdrom device with open tray and cache option

[Andrii Yaurov]

When trying to create cdrom device with open tray and either of "cache" or "discard" options specified, I get the following error:

qemu-system-x86_64: -drive if=none,id=drive-ide0-0-0,readonly=on,cache=writeback,discard=unmap,throttling.iops-total=900: Must specify either driver or file

This bug essentially forbids live migration of VMs with open cdrom trays.

I was able to find the same bug at RedHat:
https://bugzilla.redhat.com/show_bug.cgi?id=1338638

The bug was encountered in versions 2.5 and 2.11.

[John Snow (jnsnow)]

Hi, versions 2.5 and 2.11 are quite old (though version 2.10 fixed the bug mentioned in the Red Hat BZ, so I think this might be a different bug.)

It's not clear at what step this is failing or where you are seeing the error message, so:

1. What is your full command line for QEMU?
2. Do you see this error message when migrating? If so, what does the destination QEMU command line look like?
3. Does the problem reproduce on a currently-supported upstream QEMU? (4.1.1, 4.2.0)

[Launchpad Janitor (janitor)]

[Expired for QEMU because there has been no activity for 60 days.]