Zoned storage support in libvirt

Hi Peter, Zoned storage support (https://zonedstorage.io/docs/introduction/zoned-storage) is being added to QEMU. Given a zoned host block device, the QEMU syntax will look like this: --blockdev zoned_host_device,node-name=drive0,filename=/dev/$BDEV,... --device virtio-blk-pci,drive=drive0 Note that regular --blockdev host_device will not work. For now the virtio-blk device is the only one that supports zoned blockdevs. This brings to mind a few questions: 1. Does libvirt need domain XML syntax for zoned storage? Alternatively, it could probe /sys/block/$BDEV/queue/zoned and generate the correct QEMU command-line arguments for zoned devices when the contents of the file are not "none". 2. Should QEMU --blockdev host_device detected zoned devices so that --blockdev zoned_host_device is not necessary? That way libvirt would automatically support zoned storage without any domain XML syntax or libvirt code changes. The drawbacks I see when QEMU detects zoned storage automatically: - You can't easiy tell if a blockdev is zoned from the command-line. - It's possible to mismatch zoned and non-zoned devices across live migration. We still have time to decide on the QEMU command-line syntax for QEMU 8.0, so I wanted to raise this now. Thanks, Stefan