[ovs-dev] [PATCH v3 2/2] netdev-linux: Read packet auxdata to obtain vlan_tid

Ben Pfaff blp at nicira.com
Wed Dec 18 01:08:35 UTC 2013


On Mon, Dec 16, 2013 at 05:57:52PM +0900, Simon Horman wrote:
> If VLAN acceleration is used when the kernel receives a packet
> then the outer-most VLAN tag will not be present in the packet
> when it is received by netdev-linux. Rather, it will be present
> in auxdata.
> 
> This patch uses recvmsg() instead of recv() to read auxdata for
> each packet and if the vlan_tid is set then it is added to the packet.
> 
> Adding the vlan_tid makes use of headroom available
> in the buffer parameter of rx_recv.
> 
> Signed-off-by: Simon Horman <horms at verge.net.au>

This patch should be Linux-specific, why does it update netdev-bsd?

I think we should add a comment to netdev_rx_recv() explaining how the
tailroom in the buffer may get used (you might need 4 bytes more
tailroom than the actual MTU, and you might get 4 bytes of extra
headroom in the result).

Thanks,

Ben.



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