Re: [PATCH 12/18] qemu: capabilities: Add QEMU_CAPS_BLOCKDEV_HOSTDEV_SCSI
On Thu, Jul 16, 2020 at 00:16:23 +0200, Ján Tomko wrote:
On a Friday in 2020, Peter Krempa wrote:
> We want to instantiate hostdevs via -blockdev too. Add a separate
> capability for them for a clean transition. The new capability will be
> enabled when QEMU_CAPS_BLOCKDEV is present once all code is prepared.
>
What is the benefit here compared to using QEMU_CAPS_BLOCKDEV directly?
It encodes whether the particular VM instance was already started with
-blockdev used for hostdevs. The benefit ... or rather necessity is that
we need to handle cases when the VM was started with -drive differently
on hot-unplug of the hostdev.
I'd have to encode that bit of information somehow regardless of which
approach is used to actually store it.
Seems more like a libvirt capability than a QEMU capability.
It is a capability of that particular instance of the VM the same way as
others. A VM started with pre-blockdev libvirt but modern qemu will not
use -blockdev for hotplug after libvirt upgrade and this is exactly te
same situation.
Jano
> Signed-off-by: Peter Krempa <pkrempa(a)redhat.com>
> ---
> src/qemu/qemu_capabilities.c | 1 +
> src/qemu/qemu_capabilities.h | 1 +
> 2 files changed, 2 insertions(+)