[syslinux] PXE in wonderland

Geert Stappers stappers at stappers.nl
Wed Nov 14 14:22:26 PST 2007

Op 14-11-2007 om 23:24 schreef Firas Swidan, PhD:
> Hi,
> I have collected a bunch of old PII PCs that I am trying to PXE boot.
> There NICs are old and so I use etherboot floppy to emulate a native PXE
> boot. I have configured tftp, dhcpd, pxelinux, and all the other stuff.
> Everything works fine till pxelinux start booting. Then it stucks after
> printing the IP row. 
> --------------- pxelinux output -----------------------
> PXELINUX 3.10 2005-08-24 Copyright (C) 1994-2005 H. Peter Anvin
> UNDI data segment at: 0009D400
> UNDI data segment size: 1000
> UNDI data segment at: 0009E400
> UNDI data segment size: 0AB0
> PXE entry point found (we hope) at 9E40:0680
> MY IP address seems to be C0A800FC
> ip=
> --------------- pxelinux output ---------------------

Hey, there was few days ago a simular posting ...

> After downloading and struggling a bit with pxelinux assembler code, I
> found out the problem: on the top of the file cpuinit.inc that is
> included from pxelinux.asm, the instruction "int 16h" causes havoc on my
> pc. Literally, a single instruction causes the whole pc to hang.
> Amazing! Would have never believed that. Anyhow, I disabled this
> instruction, compiled, and ran pxelinux and things went fine till it
> tried to download the kernel. For some reason, tftp refused to give the
> kernel, with permission denied. Digging more, I found that this is
> related to something called "checksum offload" and accompanied with a
> checksum error. I have also noticed that my pc's keyboard does not
> function at all once pxelinux starts executing.
> Now I am not sure how to proceed. I am also wondering if the instruction
> "int 16h" has such a far reaching effects. Could it be the reason for
> the failing checksum and the not responding keyboard (after all it
> managed to stuck my whole pc)?

See at least http://en.wikipedia.org/wiki/BIOS_interrupt_call
for more information about "int 16h"

> To be concluded.
> Firas.

Some one who assumes that a poster to the mailinglist is subscribed
AND that he/she reads the mailinglist replies.

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