When using vde and large jumbo frames (mtu ~ 4K or larger) networking hangs. This is not only true for the stated qemu-kvm version but for earlier versions, too. Reproducible: Always Steps to Reproduce: 1. Use vde and do a nfs boot of the guest with rsize=8192,wsize=8192,tcp 2. Change the mtu of the guest to e.g. 9000 3. Do some network action on the guest that triggers the use of a jumbo frame. Actual Results: Networking hangs and thus the root nfs is no longer accessible. Thus the guest system hangs. It looks suspiciously as the mtu is silently kept at 1500. Frames appearing on the host vde tap interface look like this. Expected Results: No problems at all :-) See the following for a proposed fix for an older qemu version (don't think this is enough): http://www.mail-archive.com/qemu-devel@nongnu.org/msg18766.html Using tap and bridging directly instead of using vde works with larger mtus. BTW, the guest network is virtio based in both cases.
Has this seen anymore upstream traction?
Has this patch been resubmitted to upstream and gotten any feedback?
I checked: it's not upstream yet.
The patch is still not upstream. I suggest that you ping upstream about it.
Jumbo frames (65k) work great using virtio. I don't use VDE so I can't speak for it but this really needs to go to qemu.org upstream.
