Re: [PATCH 7/8] qemuxmlconftest: Update memory-hotplug-virtio-mem-s390x.xml
On 27.01.25 13:01, Boris Fiuczynski wrote:
On 1/24/25 13:35, David Hildenbrand wrote:
> On 24.01.25 13:21, Michal Privoznik wrote:
>> Drop explicit request to place virtio-mem on PCI bus from the
>> input memory-hotplug-virtio-mem-s390x.xml and demonstrate how the
>> device is automatically placed onto CCW.
>>
>
> Could it still be manually placed on the PCI bus?
>
> As of now, virtio-mem-pci is not supported on s390x -- IIRC plugging the
> device would fail -- but maybe, in a distant future it might be supported.
>
David,
Hi Boris,
the libvirt probing of capabilities with qemu
v9.2.0-1203-gd6430c17d7
returns virtio-mem-pci support based on the QOM. Should that be fixed?
Right, it's similar to virtio-balloon-pci: while it is compiled into
QEMU, plugging these devices will fail due to lack of MSI-X support. [1]
For virtio-mem-pci, in addition to MSI-X support, we'll have to wire up
the (un)plug handlers in the machine, which are currently blocked:
Which leaves us with three options:
(1) Leave it as is: device is compiled in but cannot be used, just like
virtio-balloon-pci
(2) Implement MSI-X and (un)plug support
(3) Do not compile the device in
I did a quick test with (2), but somehow the VM does not detect the
device properly. Will do some digging if it can be easily made working.
[1] https://lkml.kernel.org/r/20250115161425.246348-1-arbab@linux.ibm.com
--
Cheers,
David / dhildenb