Hi Karsten,
On Wednesday, 5 July 2017 12:51:26 CEST Karsten Horsmann wrote:
> found an very strange problem, which seems more to be an
> qemu/kvm issue. Maybe one of you knows what happens and
> give me an hint to solved this (with vio).
>
> I use an debian 9.0 kvm/qemu setup with bridge-networking.
>
> After i upgrade from debian 8.0 to 9.0 i run into a problem
> with my OpenBSD 6.0 i386, OpenBSD 6.1 i386 guests and the
> vio(4) driver.
That's weird. But I don't use i386 much anymore, so I didn't notice it so far.
It seems qemu does not send rx interrupts to the guest. It does send tx
interrupts, though. But the problem seems to occur only if vhost is used. As a
workaround set driver to 'qemu' (instead of 'vhost') in the libvirt xml:
<interface type='bridge'>
<mac address='00:11:22:33:44:00'/>
<source bridge='br0'/>
<model type='virtio'/>
<driver name='qemu'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x03'
function='0x0'/>
</interface>
A difference between i386 and amd64 is that on amd64, openbsd uses MSI-X for
virtio. Maybe legacy interrupts are broken with vhost-net. This needs some
more debugging. But its either a bug in qemu or in the linux kernel, not in
openbsd.
Cheers,
Stefan
