From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH] virtio_net: Fix MAX_PACKET_LEN to support 802.1Q VLANs
Date: Sun, 25 Jan 2009 18:06:43 -0800 (PST)
Message-ID: <20090125.180643.147283270.davem@davemloft.net>
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Cc: alex.williamson@hp.com, netdev@vger.kernel.org,
	rusty@rustcorp.com.au, kvm@vger.kernel.org
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From: Mark McLoughlin <markmc@redhat.com>
Date: Tue, 20 Jan 2009 16:59:26 +0000

> 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

Applied and queued up for -stable, thanks everyone!