On 6/2/25 11:00 AM, Peter Krempa via Devel wrote:
From: Peter Krempa <pkrempa@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 :-)