From: Yaroslav Isakov <yaroslav.isa...@gmail.com> Date: Wed, 8 Mar 2017 23:29:53 +0300
> Hello! > I've found a bug in TUN/TAP driver with offloads - when Qemu is trying > to set offloads on tap device, there is no error, but offloads are not > appied. > > The cause of this is that udev in recent systemd is using ethtool to > disable offloads. So, udev is setting tun->dev->wanted_features via > ethtool ioctl to disable TSO, but when qemu is trying to set offloads, > it's using TUN/TAP ioctl which is not setting wanted_features, so > netdev_update_features will not see features qemu wants. > > This can be easily reproduced - just run qemu with > guest_tso4=on,guest_tso6=on on systemd with systemd>=226 and after > booting the VM, ethtool -k tap0 will show that TSO4 is disabled and > TSO6 is enabled (systemd is not touching TSO6, that's why it's not > affected at all) > I've attached pretty trivial patch to fix this problem. Please read Documentation/SubmittingPatches for the proper way to submit a patch. In particular you have to provide a proper signoff tag. Thank you.
