[gPXE-devel] gPXE 1.0.0 eats DNS packets

[H. Peter Anvin]

On 06/21/2010 03:08 AM, Stefan Hajnoczi wrote:
> 
> The UDP packet is destined for an IP that is not in the ARP cache.
> gPXE does not queue UDP TX packets, it will drop the packet and
> silently ignore this return this error when no link layer destination
> is known yet (udp_xfer_deliver_iob ignores the error).
> 
> I imagine the reasoning behind ignoring the error is that application
> protocols using UDP must deal with retransmit anyway, which leads to
> the next point: I can't see PXELINUX retransmitting the DNS UDP
> packet.  The code in core/fs/pxe/dnsresolv.c has timeout logic but it
> isn't kicking in.  Any idea what is happening on the SYSLINUX side?
> 

For what it's worth, this behavior is inconsistent with vendor PXE
stacks, and has forced me to cut the timeouts significantly in PXELINUX
in order to not get unacceptable performance.  This has a somewhat bad
impact on high latency networks.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.