On Sun, 2009-10-18 at 19:32 +0200, Michael S. Tsirkin wrote:
> On Sun, Oct 18, 2009 at 12:53:56PM +0200, Michael S. Tsirkin wrote:
> > On Fri, Oct 16, 2009 at 12:29:29PM -0700, Sridhar Samudrala wrote:
> > > Hi Michael,
> > >
> > > We are trying out your vhost-net patches from your git trees on kernel.org.
> > > I am using mst/vhost.git as host kernel and mst/qemu-kvm.git for qemu.
> > >
> > > I am using the following qemu script to start the guest using userspace tap backend.
> > >
> > > home/sridhar/git/mst/qemu-kvm/x86_64-softmmu/qemu-system-x86_64 /home/sridhar/kvm_images/fedora10-1-vm -m 512 -drive file=/home/sridhar/kvm_images/fedora10-1-vm,if=virtio,index=0,boot=on -net nic,macaddr=54:52:00:35:e3:73,model=virtio -net tap,ifname=vnet0,script=no,downscript=no
> > >
> > > Now that i got the default backend to work, i wanted to try vhost in kernel. But
> > > could not figure out the right -net option to pass to qemu.
> > >
> > > Can you let me know the right syntax to start a guest using vhost.
> > >
> > > Thanks
> > > Sridhar
> >
> > Here's an example with raw socket:
> >
> > /root/kvm-test/bin/qemu-system-x86_64 -m 1G -kernel \
> > /boot/vmlinuz-$release -append \
> > 'root=UUID=d5d2d201-d086-42ad-bb1d-32fbe40eda71 ro quiet nosplash \
> > console=tty0 console=ttyS0,9600n8' -initrd /boot/guest-initrd.img \
> > $HOME/disk.raw.copy -net raw,ifname=eth3 -net nic,model=virtio,vhost \
> > -balloon none -redir tcp:8023::22
> >
> > As you see, I changed the command line.
> > You now simply add ",vhost" after model, and it will locate
> > host network interface specified earlier and attach to it.
> > This should have been clear from running qemu with -help
> > flag. Could you please suggest how can that text
> > be clarified?
I updated to your latest git trees and the default user-space tap backend using the
following -net options worked fine.
-net tap,ifname=vnet0,script=no,downscript=no -net nic,model=virtio
But i could not get vhost to work with either raw or tap backends.
I tried the following combinations.
1) -net raw,ifname=eth0 -net nic,model=virtio,vhost
2) -net raw,ifname=vnet0, -net nic,model=virtio,vhost
3) -net tap,ifname=vnet0,script=no,downscript=no -net nic,model=virtio,vhost
They all failed with the following error
vhost_net_init returned -7
This is an error message from hw/virtio-net.c:virtio_net_driver_ok() when
vhost_net_start() fails. It looks like dev->binding->irqfd() is failing in
vhost_virtqueue_init(). Haven't yet debugged further. I have CONFIG_EVENTFD
enabled in the host kernel.
Are all the above -net options supposed to work?
In your descriptions, you say that checksum/tso offload is not supported. Isn't it
possible to send/receive large packets without checksum using AF_PACKET sockets if
the attached interface supports these offloads.
Do you see the same offload issue even when using tap backend via vhost?
Thanks
Sridhar
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