[Etherboot-developers] Stack problem in start32.S

[Paul R. <pau...@lo...>]

Hi,

I just spent some time investigating a reboot problem with a customised
BIOS+Etherboot ROM. The fix really belongs in the BIOS itself (General
Software Embedded BIOS 4.3), but I think it will help add a line of code to
Etherboot.

The scenario is that on selecting "Shutdown & Restart" from Windows 9x the
machine crashes very early in the Etherboot int 19h handler.
The problem turned out to be some spurious value in the upper bits of ESP.
The fix is the instruction:
andl    $0xffff,%esp
just before the first switch from real to protected mode. At least that
fixes it for us.

Anyone else reported a restart problem like this?
--
Paul Robertson
LocSoft Limited
"The key to your embedded solutions"
www.locsoft.com
Phone +44 (0) 1793 784784
Fax     +44 (0) 1793 784789