On Tue, Oct 29, 2024 at 10:51:57AM -0400, Laine Stump wrote: > On 10/29/24 9:14 AM, Daniel P. Berrangé wrote: > > On Tue, Oct 29, 2024 at 01:09:00PM +0000, Andrea Bolognani wrote: > > > On Tue, Oct 29, 2024 at 12:46:55PM +0000, Daniel P. Berrangé wrote: > > > > A key difference that is probably relevant is that netbsd is > > > > using an e1000 NIC in QEMU, while openbsd is using a virtio-net > > > > NIC. At least when created by virt-manager. > > > > > > > > AFAIR, QEMU's magic checksum offload only happens for virtio-net, > > > > so presumably our rules are incompatible with non-virtio-net NICs > > > > in someway. > > > > > > Yes, that's it! The GNU/Hurd and Haiku guests are also using e1000, > > > since virtio drivers are not available there; moreover, if I switch a > > > random Linux guest from virtio-net to e1000 I can reproduce the issue > > > there as well. > > > > Incidentally, I think this has crossed the threshold where the cure is > > worse than the disease. > > > > We cannot ship the forthcoming libvirt release with a checksum "fix" > > that breaks all usage of NICs that aren't virtio-net, as that guarantees > > brokeness for all historical OS. > > > > If we can't quickly find a way to improve this, I think we need to > > revert (or disable) the checksum zero'ing fix for this release and > > spend more time investigating it. > > I sadly agree :-/ (although I will point out that it's not *all* non-virtio, > since e1000e seems to work). I am leaving the house now, but will make a > patch to either disable or the revert the "fix" when I get back in a few > hours. (I would rather leave it in with a switch or something so we could > continue using standard builds to test things, but that might take too long > and would definitely be too complicated for a last instant push) e1000e has support for vnet-hdr similar to virtio-net. With virtio-net, if I disable vhost-net, with <driver type=qemu> then code in virtio-net.c will manually fixup DHCP checksums. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
