[dpdk-dev] [RFC] mbuf: new flag when vlan is stripped

Olivier Matz olivier.matz at 6wind.com
Mon May 23 09:59:56 CEST 2016


Hi John,

On 05/12/2016 10:36 PM, John Daley (johndale) wrote:
>> ... This is a draft patch that implements what was previously
>> discussed, except the packet_type, which does not exist for vlan
>> today (and I think it is not mandatory for now, let's do it in
>> another patch).
>> 
>> After doing this patch, it appeared that ixgbe was the only driver
>> that had a different behavior for the PKT_RX_VLAN_PKT flag. An
>> alternative to this patch would be to only change the behavior of
>> the ixgbe driver, and just document better document the
>> PKT_RX_VLAN_PKT flags in rte_mbuf.h without adding new flags. I
>> think this is a better option.
>> 
>> Comments are welcome.
>> 
> There are applications depending on the current behavior of
> PKT_RX_VLAN_PKT as confusing as it may be.  I know of one that has
> VLAN stripping disabled and uses the flag to determine if the packet
> delivered to the app has a VLAN tag. This is actually how the flag
> behaves for ixgbe, and they patched enic and maybe other drivers to
> act accordingly. To avoid breaking the app (and any others like it),
> I think we should keep the flag behavior the same and add the new
> flag PKT_RX_VLAN_STRIPPED .

OK, thanks for your comment.
So it means the v1 will be the same than RFC. I'm submitting it.

> We should follow on with the new packet type since it enables a nice
> performance improvement by not forcing apps to break open the packet
> just to see if there is a VLAN tag.

Yep, agree.

Thanks,
Olivier


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