Re: [libvirt] How to enable vhost for virtIO NIC?
Hi all,
On Wed, May 19, 2010 at 18:22, Laine Stump <laine(a)laine.org> wrote:
On 05/19/2010 01:49 AM, Huang, Zhiteng wrote:
>
> Hi gurus on the list,
>
> I'm trying to bring up a Linux with virtio vhost backend. My system is
> running on kernel 2.6.34-rc7, libvirt 0.8.0.
>
> Two questions regarding to vhost:
>
> 1) XML format for vhost
> I didn't find any documents on libvirt.org description the XML or QMU
> argument format for vhost.
If you're using virtio networking, and vhost-net support is available on
your system, libvirt will automatically alter the qemu commandline arguments
to take advantage of it. libvirt checks for two things:
1) it runs "qemu-kvm --help" and looks for ",vhost=" in the output
(demonstrating that this build of qemu supports vhost)
2) it attempts to open "/dev/vhost-net" in rw mode (demonstrating that the
kernel support is there, either built into the kernel or loaded as a
module).
I just tried this with libvirt 0.8.1, on a 2.6.34 kernel, and it
doesn't seem to work for me.
Setting a breakpoint on the qemudOpenVhostNet function shows that it
returns -1, because QEMUD_CMD_FLAG_NETDEV isn't set.
-netdev is disabled on qemu 0.12
Ruben