Re: [PATCH] qemu: command: Don't attempt to set backend MTU for networks which don't use host backend directly
On 6/2/25 11:00 AM, Peter Krempa via Devel wrote:
From: Peter Krempa <pkrempa(a)redhat.com>
Attempting to set MTU for network types which don't actually use the
network device on the host results in a failure. The 'mtu' property is
also used e.g. for the 'host_mtu' property of e.g. 'virtio-net-pci'
which is applied even in vhost-user mode.
Use the existing switch which selects devices without a network device
backend on the host side and skip setting the MTU.
It's disturbing that this points out I had added the necessary code to
add "--mtu" to the passt commandline when <mtu size='blah'/> was
specified, but apparently had never tested it (because it would have
failed) :-/
Anyway, on the upside, according to Stefano it's always best to leave
mtu unspecified for passt interfaces, because it then defaults to some
gigantic number that gives the best performance :-)
(Oh, BTW I built with and without your patch, with the expected results :-)