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Date: Fri, 11 Feb 2011 09:26:50 +0100
From: Anthony Liguori <anthony@codemonkey.ws>
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Subject: Re: [Qemu-devel] [PATCH] slirp: ensure minimum packet size
References: <4D540A3402000048000A9C8C@novprvoes0310.provo.novell.com>
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To: Bruce Rogers <brogers@novell.com>
Cc: qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>

On 02/10/2011 11:54 PM, Bruce Rogers wrote:
> With recent gpxe eepro100 drivers, short packets are rejected,
> so ensure the minimum ethernet packet size.
>
> Signed-off-by: Bruce Rogers<brogers@novell.com>
>    

This doesn't make much sense.  I think this is more likely a case where 
we're incorrectly calculating packet size.  Michael fixed an issue 
similar to this in e1000 relating to FCR if I recall correctly.  Maybe 
eepro100 has the same problem?

Regards,

Anthony Liguori

> ---
>   slirp/slirp.c |    4 ++--
>   1 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/slirp/slirp.c b/slirp/slirp.c
> index 332d83b..b611cf7 100644
> --- a/slirp/slirp.c
> +++ b/slirp/slirp.c
> @@ -697,7 +697,7 @@ void if_encap(Slirp *slirp, const uint8_t *ip_data, int ip_data_len)
>           return;
>
>       if (!memcmp(slirp->client_ethaddr, zero_ethaddr, ETH_ALEN)) {
> -        uint8_t arp_req[ETH_HLEN + sizeof(struct arphdr)];
> +        uint8_t arp_req[max(ETH_HLEN + sizeof(struct arphdr), 64)];
>           struct ethhdr *reh = (struct ethhdr *)arp_req;
>           struct arphdr *rah = (struct arphdr *)(arp_req + ETH_HLEN);
>           const struct ip *iph = (const struct ip *)ip_data;
> @@ -734,7 +734,7 @@ void if_encap(Slirp *slirp, const uint8_t *ip_data, int ip_data_len)
>           memcpy(&eh->h_source[2],&slirp->vhost_addr, 4);
>           eh->h_proto = htons(ETH_P_IP);
>           memcpy(buf + sizeof(struct ethhdr), ip_data, ip_data_len);
> -        slirp_output(slirp->opaque, buf, ip_data_len + ETH_HLEN);
> +        slirp_output(slirp->opaque, buf, max(ip_data_len + ETH_HLEN, 64));
>       }
>   }
>
>