about VGA support in voyager2 board

SONE Takeshi ts1 at cma.co.jp
Wed Aug 27 02:58:01 CEST 2003

On Tue, Aug 26, 2003 at 11:00:27PM -0600, ron minnich wrote:
> On Wed, 27 Aug 2003, elife elife wrote:
> >   I am trying to add VGA support in cocom voyager2 board. The VGA is found 
> > but lb complain "biosint: Unsupport int #0x6" endlessly. I dumped the 
> > original bios and found besides VGA BIOS I extracted, there is VSA driver. 
> > Is VSA driver also needed to work with linuxbios and VGA BIOS? If so, Where 
> > should I put it? And need I do more things to make it work?
> you need to confirm that int #5 is a VSA interrupt of some sort. 

I don't know what VSA is, but int 6 is the Invalid Opcode Exception,
not a BIOS service.
This means the execution crashed.

Btw, I've noticed that the idt.c (realmode int handler) puts
"stub"s starting at 0x400 (1024). It installs 256 stubs, 9 bytes each,
so they occupy 256*9=2304 bytes from 0x400.
The 256 bytes (or more?) starting at 0x400 is the BIOS Data Area,
and VGABIOS tends to rewrite some bytes in it.
So, it might damage the int handler before calling it.

I don't know if this is the case, but the stubs can easily be moved
anywhere below 64k, I think.


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