[syslinux] Failure to boot isohybrid image from USB stick

[H. Peter Anvin]

Thomas Schmitt wrote:
> Hi,
> 
> Gilles Espinasse wrote:
>> Wich bios version did you have actually?
> 
> The first one says "Award A7V8-X ACPI BIOS
> Revision 1008 12/29/2003".

Figures.  This BIOS has some very interesting braindamage when it comes 
to USB booting.

> The second one (started by the first when
> finding the IDE controller, i assume) says:
> "Ultra133TX2 2.20.0.15  1999-2001 Promise Inc."
> 
> The latter offers me a menu of boot devices
> if i press some keys (probably Del or Space
> does the trick). This menu offers "USB ZIP"
> if the USB stick is plugged in. After selecting
> that item once, the system reacted on the
> USB stick at boot time. Previous to that it
> ignored the stick.
> But it boots RIP 7.0 only if it was repacked
> by RIP's mkusb.sh. 
> 
> I am currently trying to find out how
> the parasite BIOS gets started and whether
> i can disable this without touching the
> shaky hardware. They call it "BIOS" not
> "bootloader".
> 

It's called an "expansion BIOS" and resides on a ROM on the card.  It's 
usually hard to disable without removing the card.  However, it is 
unlikely to actually be the cause, so I wouldn't worry too much about it.

First of all, please try a different *brand* USB stick.  It is somewhat 
important to know if the braindamage depends on the USB stick 
microcontroller.

Second, tracking down the actual problem -- or rather, a suitable 
workaround -- probably will take adding a bunch of debugging code to 
isohybrid and then applying some decent guesswork.  Given that I'm 
currently unemployed, I don't know how much time I will be able to spend 
on that, since obviously the job hunt goes first.

	-hpa