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From:   Jason Xing <kerneljasonxing@gmail.com>
Date:   Wed, 1 Feb 2023 21:28:44 +0800
Message-ID: <CAL+tcoD94KByy-Xz=ZiCt5gXZ0YhOjWU=vrOzRxezwRtuQmcJw@mail.gmail.com>
Subject: Re: [Intel-wired-lan] [PATCH v2 net] ixgbe: allow to increase MTU to
 some extent with XDP enabled
To:     Alexander Lobakin <alexandr.lobakin@intel.com>
Cc:     Maciej Fijalkowski <maciej.fijalkowski@intel.com>,
        jesse.brandeburg@intel.com, anthony.l.nguyen@intel.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, richardcochran@gmail.com, ast@kernel.org,
        daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com,
        netdev@vger.kernel.org, linux-kernel@vger.kernel.org,
        intel-wired-lan@lists.osuosl.org, bpf@vger.kernel.org,
        Jason Xing <kernelxing@tencent.com>
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On Wed, Feb 1, 2023 at 7:15 PM Alexander Lobakin
<alexandr.lobakin@intel.com> wrote:
>
> 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.
>

Roger that, I will write another patch with your suggestions (labeled
'suggested-by your email address').

Thanks,
Jason

> >
> > 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
>