Re: vga bios initialization entry point

On Apr 21, 11:43 am, Cyril Novikov  <spamt...@[EMAIL PROTECTED]
> wrote:
> stam...@[EMAIL PROTECTED]
 wrote:
> > Hi,
>
> > My desktop machine has an Intel integrated vga chip:
> > 00:02.0 VGA compatible controller: Intel Cor****ation 82G965 Integrated
> > Graphics Controller (rev 02)
>
> > I disassembled the code at C000: and got this:
> > 0000c0000 55               push bp
> > 0000c0001 aa               stosb
> > 0000c0002 58               pop ax
> > 0000c0003 e919a8           jmp 0xba81f
> > How come the vga bios jumps to code that starts at an address that is
> > smaller than C0000?
> > The jump at C0014 jumps to some code that looks like the card's actual
> > initialization code. Any reason why this jmp is placed at offset 14h ?
>
> > Anyone here got any idea what I'm seeing?
>
> What makes you think the code at c0000 is executable? "55 aa" looks like
> some signature.

OK.
I wasn't clear enough.

The pci spec says that:
the first two signature bytes are 0x55 & 0xaa
the third byte is the size of the code in 512 byte units
the 4th byte and upwards is the expansion bios entry (this is
actually
    platform dependent and i think is described in the pci-sig x86
binding).


thanks,
s