Re: [PATCH] kvm: qemu: Handle tap fds with IFF_VNET_HDR

Mark McLoughlin
2008-08-21T09:31:00Z

On Wed, 2008-08-20 at 20:51 +0300, Avi Kivity wrote:
> Anthony Liguori wrote:
> > Mark McLoughlin wrote:
> >> Allow users to pass an IFF_VNET_HDR tap fd via "-net tap,fd=X"
> >> by querying the fd with the recently added TUNGETIFF ioctl() to
> >> see if IFF_VNET_HDR has been enabled.
> >>
> >> Note: users wishing to pass an IFF_VNET_HDR tap fd to qemu
> >> should check both that a) this version of qemu can handle
> >> such an fd and b) that the TUNGETIFF ioctl() is available in
> >> the running kernel.
> >>
> >> We add a comment to the "qemu -help" output to indicate to
> >> users that this version of qemu supports IFF_VNET_HDR.
> >>
> >
> > The -help output is not a supported interface. An info command in the
> > monitor would be a better way to detect this.
> >
>
> You need to know this before you create a virtual machine. I suggested
> a 'qemu -capabilities' thing to describe what this qemu can do.

I'll take a stab at "-capabilities" later.

In the mean time, it may make sense to commit the patch minus the -help
string.

Cheers,
Mark.