[ovs-dev] Queuing packets to userspace and NBL info problem

Ben Pfaff blp at nicira.com
Sun Aug 3 17:10:57 UTC 2014

On Sun, Aug 03, 2014 at 05:06:14PM +0000, Samuel Ghinet wrote:
> I think this is a problem that both implementations suffer of: Namely,
> when we give a packet to the userspace, we strip off the NBL info
> array from it. In other words, when the packet gets back from the
> userspace and must be outputted to ports, all NBL info that it had
> before is cleared out.
> We can handle manually NBL info such as checksum offload or LSO. But
> normally, all other NBL info in the array are important, and we cannot
> simply strip them away.

On Linux, the "sk_buff" kernel data structure used for packets has tons
of extra info that gets stripped when the packet goes to userspace.  It
doesn't cause a problem.  What is different the Windows NBL?

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