netdev - Re: [RFC PATCH 4/5] bnxt: Add support for segmentation of tunnels with outer checksums

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Date:	Wed, 27 Apr 2016 21:32:38 -0700
From:	Michael Chan <michael.chan@...adcom.com>
To:	Alexander Duyck <alexander.duyck@...il.com>
Cc:	Alexander Duyck <aduyck@...antis.com>, eugenia@...lanox.com,
	Bruce W Allan <bruce.w.allan@...el.com>,
	Saeed Mahameed <saeedm@...lanox.com>,
	Netdev <netdev@...r.kernel.org>,
	intel-wired-lan <intel-wired-lan@...ts.osuosl.org>,
	Ariel Elior <ariel.elior@...gic.com>,
	Michael Chan <mchan@...adcom.com>
Subject: Re: [RFC PATCH 4/5] bnxt: Add support for segmentation of tunnels
 with outer checksums

On Wed, Apr 27, 2016 at 8:21 AM, Alexander Duyck
<alexander.duyck@...il.com> wrote:
> On Tue, Apr 26, 2016 at 10:55 PM, Michael Chan
> <michael.chan@...adcom.com> wrote:
>> On Tue, Apr 19, 2016 at 12:06 PM, Alexander Duyck <aduyck@...antis.com> wrote:
>>> This patch assumes that the bnxt hardware will ignore existing IPv4/v6
>>> header fields for length and checksum as well as the length and checksum
>>> fields for outer UDP and GRE headers.
>>>
>>> I have no means of testing this as I do not have any bnx2x hardware but
>>> thought I would submit it as an RFC to see if anyone out there wants to
>>> test this and see if this does in fact enable this functionality allowing
>>> us to to segment tunneled frames that have an outer checksum.
>>>
>>> Signed-off-by: Alexander Duyck <aduyck@...antis.com>
>>
>> Hi Alex, I just did a very quick test of this patch on our bnxt
>> hardware and it seemed to work.
>>
>> I created a vxlan endpoint with udpcsum enabled and I saw TSO packets
>> getting through.  I've verified that our hardware can be programmed to
>> either ignore outer UDP checksum or to calculate it.  Current default
>> is to ignore ipv4 UDP checksum and calculate ipv6 UDP checksum.
>> Thanks.
>
> Are you saying you can natively support UDP tunnel with outer checksum
> offload then?

Yes.  Calculate or ignore the outer UDP checksum.

>
> I'm just trying to sort out if you actually need to have the partial
> segmentation offload support or if we can handle it in hardware.  Also
> is there any documentation you could point me to that might help to
> clarify what the hardware does/doesn't support so that I could improve
> upon this patch in order to make sure we are getting the most bang for
> the buck in terms of the features that can be offloaded by hardware?

No public documentation yet.  I think the plan is to publish the
programmer's reference on our website at some point in the future.