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

[James Courtier-Dutton]

Dag Wieers wrote:
> On Wed, 21 Jan 2004, Dag Wieers wrote:
> 
> 
>>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.
>>
>>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 ?
> 
> 
> I've now tried booting a Linux boot image via memdisk to see if that would 
> work. And it does. What's the difference between DOS and Linux that could 
> cause MSDOS, PCDOS and FreeDOS to freeze when booted from a USB stick ? 
> BIOS disk-access ?
> 
> Is there some way to force Linux to use the BIOS for disk-access so that I 
> could test this to see if Linux would suffer from the same 
> bug/incompatibility in memdisk/BIOS ?
> 
> It would be nice if this was possible so that Linux could access certain 
> RAID/SCSI hardware without needing a specific driver, just like DOS. (Of 
> course it would be slow, but you would have an alternative)
> 
> Any help would be greatly appreciated !
> 
> Kind regards.
> --   dag wieers,  dag at wieers.com,  http://dag.wieers.com/   --
> [Any errors in spelling, tact or fact are transmission errors]
> 

It would seem to me that the easiest way to trace this problem is to put 
a lot of printf statements in the freedos code, so that everytime it 
accesses int13 or tries to read the disc, a nice message it displayed.
At least then you could start finding out which int13 call is causing 
the problems, and maybe then hack memdisc to fix the buggy int13 call.

Cheers
James