Support initrdless boot on default qemu virt models and openstack

[Dimitri John Ledkov]

Currently qemu & openstack for the most simple invocations of "virtio" drive type use virtio-blk.
One can use virtio-scsi, and many do, but it's not a given.
To continue support minimal images without initrd, and enable in-place no-change migration, we should also make virtio-blk builtin.

This can be revisited once openstack & qemu defaults change to virtio-scsi (if ever).

Test cases:

Qemu with `-drive if=virtio,format=$format,file=$image` should work, requires virtio-blk today.

Qemu with `-device virtio-scsi-pci,id=scsi0 \
-drive if=none,id=rootfs,format=$format,file=$image -device scsi-hd,drive=rootfs,bus=scsi0.0"` already works, requires virtio-scsi, and should continue to work.

Openstack with

openstack image create \
     --container-format bare \
     --disk-format qcow2 \
     --file my-minimal.qcow2

should work and currently requires virtio-blk.

Openstack with

openstack image create \
     --container-format bare \
     --disk-format qcow2 \
     --property hw_disk_bus=scsi \
     --property hw_scsi_model=virtio-scsi \
     --file my-minimal.qcow2

already works, and should continue to work, requires virtio-scsi.

[Philip Roche (philroche)]

Note that this is blocking the publication of new Mantic minimized cloud images as we gate on being able to test with the default OpenStack configuration which is virtio-blk based.

[Dimitri John Ledkov (xnox)]

submitted at https://lists.ubuntu.com/archives/kernel-team/2023-August/141957.html

[Launchpad Janitor (janitor)]

This bug was fixed in the package linux - 6.5.0-5.5

---------------
linux (6.5.0-5.5) mantic; urgency=medium

  * mantic/linux: 6.5.0-5.5 -proposed tracker (LP: #2034546)

  * Packaging resync (LP: #1786013)
    - [Packaging] update helper scripts
    - debian/dkms-versions -- update from kernel-versions (main/d2023.08.23)

 -- Andrea Righi <email address hidden> Wed, 06 Sep 2023 15:51:04 +0200