Any chance this made it into 3.0.3?
It'd be really nice to be able to set MTU 9000 for some free performance
improvements for iSCSI.
Thanks,
Dmitri
> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
> Daniele Palumbo
> Sent: Wednesday, September 13, 2006 10:55 AM
> To: xen-users@xxxxxxxxxxxxxxxxxxx
> Cc: xen-devel
> Subject: Re: [Xen-users] Ethernet MTU
>
>
> I have some news...
>
> On Wednesday 16 August 2006 22:53, Dominique Rousseau wrote:
> > After some tries, it looks like the vif code don't handle
> frames with
> > size larger than 1500.
>
> true:
> http://lists.xensource.com/archives/html/xen-devel/2006-08/msg
> 00944.html
>
> > Looking at the code, there is the following snippet that
> seems to be
> > the probleme (in drivers/xen/netback/netback.c) :
> >
> > if (unlikely(txreq.size < ETH_HLEN) ||
> > unlikely(txreq.size > ETH_FRAME_LEN)) {
> > DPRINTK("Bad packet size: %d\n", txreq.size);
> > make_tx_response(netif, txreq.id,
> NETIF_RSP_ERROR);
> > netif_put(netif);
> > continue;
> > }
>
> ./include/linux/if_vlan.h:#define VLAN_ETH_FRAME_LEN 1518
> /* Max. octets
> in frame sans FCS */
> ./include/linux/if_ether.h:#define ETH_FRAME_LEN 1514
> /*
> Max. octets in frame sans FCS */
>
> ./include/linux/if_vlan.h:#define VLAN_ETH_HLEN 18
> /* Total
> octets in header. */
> ./include/linux/if_ether.h:#define ETH_HLEN 14
> /* Total
> octets in header. */
>
> netfront_vlan.patch:
> ---
> # Node ID a5ee1cb525bbe8954dc3332ceec951e09a378b68
> # parent: c097485037f7417b77db34da198b62a9c9481dc5
> Make MTU rx check in netfront more permissive to allow for
> 8021q vlan tagging.
>
> Signed-off-by: Keir Fraser <keir@xxxxxxxxxxxxx>
>
> --- a/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
> Wed Mar 15
> 12:41:58 2006 +0100
> +++ b/linux-2.6-xen-sparse/drivers/xen/netfront/netfront.c
> Wed Mar 15
> 12:52:33 2006 +0100
> @@ -845,11 +845,11 @@ static int netif_poll(struct net_device
> }
>
> while ((skb = __skb_dequeue(&rxq)) != NULL) {
> - if (skb->len > (dev->mtu + ETH_HLEN)) {
> + if (skb->len > (dev->mtu + ETH_HLEN + 4)) {
> if (net_ratelimit())
> printk(KERN_INFO "Received
> packet too big
> for "
> "MTU (%d > %d)\n",
> - skb->len - ETH_HLEN, dev->mtu);
> + skb->len - ETH_HLEN - 4,
> + dev->mtu);
> skb->len = 0;
> skb->tail = skb->data;
> init_skb_shinfo(skb);
> ---
>
> looking at all that things, maybe the solutions is to change
> ETH_FRAME_LEN in
> VLAN_ETH_FRAME_LEN...
> or to remove that check (already done in unstable).
>
> i'll try tomorrow.
>
> bye
> d.
>
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