GNAT/RTEMS pc386 - BIOS functions

[Chris Caudle]

>===== Original Message From Alejandro Villanueva <190921 at cepsz.unizar.es> 
=====
>Thanks Chris, but... how do I get back to real mode?

That I don't remember.  You'll have to dig into the Intel manuals for that, 
but I usually stay away from it.  You will probably have to save your current 
register state, and restore it when you come back.  Jumping back and forth 
between real and protected mode is pretty messy.

I just rememberd that the PC386 BSP uses bios calls for PCI access.
Checking in c/src/lib/libbsp/i386/shared/pci/pcibios.c I see that it relies on 
the presence of BIOS-32, the 32 bit bios extension.
I don't have any familiarity with BIOS-32, but if you can find that 
specification, and if it includes a method of accessing interrupt 13, 
pcibios.c will show you how to do it without having to switch back and forth 
between real and protected mode.

hope that helps,
Chris Caudle