[gPXE-devel] gPXE 1.0.0 eats DNS packets

[Stefan Hajnoczi]

On Mon, Jun 21, 2010 at 9:33 AM, Stefan Hajnoczi <stefanha at gmail.com> wrote:
> On Mon, Jun 21, 2010 at 8:38 AM, H. Peter Anvin <hpa at zytor.com> wrote:
>> I just discovered that gPXE 1.0.0 eats DNS packets sent via the UDP
>> interface.  This is somewhat puzzling to me, since the DNS packet
>> doesn't even make it out the wire (it would have made more sense if the
>> reply had been received, but a packet sniffer shows nothing on egress.)
>>  Removing gPXE (undionly.kkpxe) and running on the raw vendor stack
>> eliminates this problem.
>>
>> This is threatening to become a showstopper for Syslinux 4.00, so I
>> would really appreciate assistance in tracking this down.
>
> Is there a simple setup to reproduce this?

Okay, here is a setup that reproduces the issue:

1. Build syslinux.git/master (includes gPXE 1.0.0)
2. Put gpxelinux.0 and host.c32 in the TFTP server visible directory
3. kvm -boot n -tftp $tfp_dir -bootp gpxelinux.0
4. At the PXELINUX prompt: host.c32 vmsplice.net
5. Wait forever for DNS reply...

When gPXE is built with DEBUG=pxe_udp there is lots of output as
host.c32 and the DNS code in PXELINUX waits for a UDP reply.

Stefan