Re: [Intel-wired-lan] [PATCH v2 net] ixgbe: allow to increase MTU to some extent with XDP enabled

[Alexander Lobakin <alexandr.lobakin@intel.com>]

From: Jason Xing <kerneljasonxing@gmail.com>
Date: Tue, 31 Jan 2023 19:23:59 +0800

> On Tue, Jan 31, 2023 at 7:08 PM Alexander Lobakin
> <alexandr.lobakin@intel.com> wrote:

[...]

>>>> You said in this thread that you've done several tests - what were they?
>>>
>>> Tests against XDP are running on the server side when MTU varies from
>>> 1500 to 3050 (not including ETH_HLEN, ETH_FCS_LEN and VLAN_HLEN) for a
>>
> 
>> BTW, if ixgbe allows you to set MTU of 3050, it needs to be fixed. Intel
>> drivers at some point didn't include the second VLAN tag into account,
> 
> Yes, I noticed that.
> 
> It should be like "int new_frame_size = new_mtu + ETH_HLEN +
> ETH_FCS_LEN + (VLAN_HLEN * 2)" instead of only one VLAN_HLEN, which is
> used to compute real size in ixgbe_change_mtu() function.
> I'm wondering if I could submit another patch to fix the issue you
> mentioned because the current patch tells a different issue. Does it
> make sense?

Yes, please send as a separate patch. It's somewhat related to the
topic, but better to keep commits atomic.

> 
> If you're available, please help me review the v3 patch I've already
> sent to the mailing-list. Thanks anyway.
> The Link is https://lore.kernel.org/lkml/20230131032357.34029-1-kerneljasonxing@gmail.com/
> .
> 
> Thanks,
> Jason

Thanks,
Olek