[syslinux] Bug-report: Booting DOS images from USB

[Dag Wieers]

On Tue, 20 Jan 2004, H. Peter Anvin wrote:

> Dag Wieers wrote:
> > 
> > I can try later on a T23 too, but I fear that it won't make a difference.
> > Is it possible that all the Thinkpads have this failure, or is it maybe 
> > some conflict between memdisk and the BIOS that has not been discovered 
> > yet ?
> 
> It's entirely possible.  USB and BIOS actually match extremely poorly,
> and what I've seen of BIOS code indicate that most USB support is a
> total hatchet job.

Ok, FWIW, here's another output from a Thinkpad T23 trying to load FreeDOS 
from syslinux 2.08.

*	FreeDOS: (what I have on the screen!):

	e820: 00000000ffc00000 0000000000400000 2
	Ramdisk at 0x1ff20000, length 0x00104a22b
	Moving compressed data from 0x1ff20000 to 0x1fdbdc00
	gzip image: decompressed addr 0x1fe08000, len 0x00168000: ok
	command line: initrd=freedos.igz BOOT_IMAGE=memdisk.zi
	Disk is floppy, 1440 K, C/H/S = 80/2/18
	Total size needed = 1458 bytes, allocating 2K
	Old dos memory at 0x9f000 (map says 0x9f000), loading at 0x9e800
	1588: 0xffff  15E801: 0x3c00 0x1ee0
	INT 13 08: Success, count = 1, BPT = f000:91a3
	old: int13 = f0006bd8  int15 = f0006bdd
	new: int13 = 9e800008  int15 = 9e800272
	Loading boot sector... booting...
	FreeDOS kernel version 1.1.32a (Building 2032a) [Sep 24 2003 21:58:48]
	Kernel compatibility 7.10 - WATCOMC - FAT32 support

	(C) Copyright 1995-2003 Pasquale J. Villani and The FreeDOS Project.
	All Rights Reserved. This is free software and ....ladadi ladada
	....
	either version 2, or (at your option) any later version.
	 - InitDisk
	Invalid Opcode at 0073 FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFF FFFFF FFFF FF
	FF

I also tried it on a T40 and the same results. The T23 doesn't return the 
'interrupt divide by zero' error but this Invalid Opcode. I still hope to 
provide you with enough information to make this work.

Please tell me what you would do to analyse memdisk's behaviour ? Is there 
a verbose option I can enable to send you some output ?

What I do find strange is that the image is loaded from USB in RAM and USB 
isn't necessary anymore to boot the image. So why does it work over 
pxelinux and isolinux while the next stages don't use the USB directly 
anymore.

Could we disable the USB-stick after the DOS image is loaded in RAM so 
that DOS doesn't try to access it (or use it as a normal harddisk) ? That 
would at least make it continue to load DOS.

Thanks in advance,
--   dag wieers,  dag at wieers.com,  http://dag.wieers.com/   --
[Any errors in spelling, tact or fact are transmission errors]