Syslinux - Jul 2019 - PXELINUX gets stuck when receiving non-PXE traffic

On 6/6/19 8:16 AM, Ady Ady via Syslinux wrote:
> 
>> the PXELINUX log line is
>> printed (PXELINUX 6.04 lwIP 6.04-pre3 Copyright (C) 1994-2015 H. Peter
>> Anvin et al),
> 
> (snip)
> 
> FWIW, the official binaries from 6.04-pre2 and 6.04-pre3 are not good 
> for troubleshooting.
> 
> Is the same behavior present when testing with other versions? I would 
> suggest trying 6.04-pre1, and/or the binaries from Debian Sid / 
> Unstable (which are more up-to-date than official upstream 6.04-pre1). 
> Please note that you need to replace _all_ binaries (e.g. *.c32), not 
> just lpxelinux.0, from the same exact build/version/package.
> 
Indeed; it would also be a good idea to test both pxelinux.0 and lpxelinux.0.
They access the PXE stack in very different ways, so it is a good idea to
check both.

	-hpa

Hi hpa, Ady,

hpa at zytor.com (H. Peter Anvin) writes:
> On 6/6/19 8:16 AM, Ady Ady via Syslinux wrote:
>> 
>>> the PXELINUX log line is
>>> printed (PXELINUX 6.04 lwIP 6.04-pre3 Copyright (C) 1994-2015 H.
Peter
>>> Anvin et al),
>> 
>> (snip)
>> 
>> FWIW, the official binaries from 6.04-pre2 and 6.04-pre3 are not good 
>> for troubleshooting.
>> 
>> Is the same behavior present when testing with other versions? I would 
>> suggest trying 6.04-pre1, and/or the binaries from Debian Sid / 
>> Unstable (which are more up-to-date than official upstream 6.04-pre1). 
>> Please note that you need to replace _all_ binaries (e.g. *.c32), not 
>> just lpxelinux.0, from the same exact build/version/package.
Thanks for letting me know. I have repeated my tests with 6.04-pre1 and
Debian unstable?s 3:6.04~git20190206.bf6db5b4+dfsg1-1. Both versions
exhibit the same problem.
> Indeed; it would also be a good idea to test both pxelinux.0 and
lpxelinux.0.
> They access the PXE stack in very different ways, so it is a good idea to
> check both.
I can confirm that using pxelinux.0 instead of lpxelinux.0 does indeed
work in my setup! I will switch to pxelinux.0 for the time being.

I tried enabling debug output by using:

echo 'GCCWARN += -DDEBUG_PORT=0x3f8 -DCORE_DEBUG=1' >> mk/devel.mk

?but unfortunately I don?t see any additional messages on the serial
console except for the initial message:

PXELINUX 6.04 lwIP  Copyright (C) 1994-2015 H. Peter Anvin et al

Do you happen to know off-head what might be wrong here? As a quick
reminder, the hardware I?m running this on is a
https://pcengines.ch/apu2c4.htm

Thanks!

-- 
Best regards,
Michael

On 7/18/19 10:30 AM, Michael Stapelberg via Syslinux
wrote:
>>>
>>> Is the same behavior present when testing with other versions? I
would
>>> suggest trying 6.04-pre1, and/or the binaries from Debian Sid / 
>>> Unstable (which are more up-to-date than official upstream
6.04-pre1).
>>> Please note that you need to replace _all_ binaries (e.g. *.c32),
not
>>> just lpxelinux.0, from the same exact build/version/package.
> 
> Thanks for letting me know. I have repeated my tests with 6.04-pre1 and
> Debian unstable?s 3:6.04~git20190206.bf6db5b4+dfsg1-1. Both versions
> exhibit the same problem.
> 
>> Indeed; it would also be a good idea to test both pxelinux.0 and
lpxelinux.0.
>> They access the PXE stack in very different ways, so it is a good idea
to
>> check both.
> 
> I can confirm that using pxelinux.0 instead of lpxelinux.0 does indeed
> work in my setup! I will switch to pxelinux.0 for the time being.
> 
> I tried enabling debug output by using:
> 
> echo 'GCCWARN += -DDEBUG_PORT=0x3f8 -DCORE_DEBUG=1' >>
mk/devel.mk
> 
> ?but unfortunately I don?t see any additional messages on the serial
> console except for the initial message:
> 
> PXELINUX 6.04 lwIP  Copyright (C) 1994-2015 H. Peter Anvin et al
> 
> Do you happen to know off-head what might be wrong here? As a quick
> reminder, the hardware I?m running this on is a
> https://pcengines.ch/apu2c4.htm
> 
Hi,

lpxelinux.0 interacts with the network ROM in a completely different way than
pxelinux.0.  In general, the method used by pxelinux.0 is likely to be *far*
more reliable given the crazy variety of PXE ROMs out there; however, it can
inherently only use UDP and therefore only supports TFTP. For that reason, I
strongly recommend that people use lpxelinux.0 only if you intend to boot from
a non-TFTP protocol (i.e. HTTP or FTP.)

	-hpa