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

Avi Kivity
2008-08-20T17:51:59Z

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.

--
Do not meddle in the internals of kernels, for they are subtle and quick to panic.