[syslinux] Syslinux Bootsector

[H. Peter Anvin]

martin at weh.rwth-aachen.de wrote:
> Hi!
> 
> Facing a strange problem about not being able to access
> the floppy drive after booting from a rescue-floppy with
> 2.2.x kernel on an asus p4te mainboard, i searched the
> net and found a bug in the bootsector of the 2.2.x kernels.
> Before control is redirected to the kernel, the floppy drive
> is shut down in a way, that freezes the FD-Controller on
> recent mainboards (like the ASUS P4T-E).
> The Syslinux-Bootsector (at least until version 1.72) uses
> the same method of "stopping" the floppy; this makes the
> installation with multiple floppies impossible.
> I'd like to submit a change of the SysLinux Bootsector that
> is based on the newer 2.4.x kernel approaches to that problem
> and worked fine for me:
> 
> ;
> ; Linux wants the floppy motor shut off before starting the kernel,
> ; at least bootsect.S seems to imply so
> ;
> kill_motor:
>               push ax
>               push dx
>               xor ax,ax
>               xor dx,dx
>               int 13h
> 	      pop dx
> 	      pop ax
> 
> instead of
> 
>               mov dx,03F2h
> 	      xor al,al
> 	      call slow_out
> 

Looks sensible.  In fact, that particular poking directly on the floppy 
controller has been bugging me for quite a while... it's simply not the 
Right Thing to do since you don't know for sure that the int 13h device 
and the hardware floppy is the same thing, especially not in the 
presence of IDE/USB floppy or things like MEMDISK.

	-hpa