GNAT/RTEMS pc386 - BIOS functions

[Joel Sherrill]

Chris Caudle wrote:
> 
> >===== 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.

If anyone can get this working with a disk, please let me know.

> hope that helps,
> Chris Caudle

-- 
Joel Sherrill, Ph.D.             Director of Research & Development
joel at OARcorp.com                 On-Line Applications Research
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