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From: Mark McLoughlin <markmc@redhat.com>
To: Alex Williamson <alex.williamson@hp.com>
Cc: netdev@vger.kernel.org, rusty@rustcorp.com.au, kvm@vger.kernel.org
Subject: Re: [PATCH] virtio_net: Fix MAX_PACKET_LEN to support 802.1Q VLANs
Date: Tue, 20 Jan 2009 16:59:26 +0000	[thread overview]
Message-ID: <1232470766.5277.18.camel@blaa> (raw)
In-Reply-To: <20090120164822.10112.89512.stgit@debian.lart>

On Tue, 2009-01-20 at 09:48 -0700, Alex Williamson wrote:

> 802.1Q expanded the maximum ethernet frame size by 4 bytes for the
> VLAN tag.  We're not taking this into account in virtio_net, which
> means the buffers we provide to the backend in the virtqueue RX ring
> aren't big enough to hold a full MTU VLAN packet.  For QEMU/KVM,
> this results in the backend exiting with a packet truncation error.
> 
> Signed-off-by: Alex Williamson <alex.williamson@hp.com>

Acked-by: Mark McLoughlin <markmc@redhat.com>

Note 1: this only matters if the guest isn't using mergeable receive
buffers or GSO

Note 2: IMHO, this should go in 2.6.29 and stable

Cheers,
Mark.


  reply	other threads:[~2009-01-20 16:59 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2009-01-20 16:48 [PATCH] virtio_net: Fix MAX_PACKET_LEN to support 802.1Q VLANs Alex Williamson
2009-01-20 16:59 ` Mark McLoughlin [this message]
2009-01-26  2:06   ` David Miller

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