[OpenBIOS] Video

[Edwin Rhodes]

why dont you have a look at the bocus ibm pc emulator, that boots an image
of the elpin vga bios, see how bocus does it.

----- Original Message -----
From: Jeff Garzik <jgarzik at mandrakesoft.com>
To: <openbios at elvis.informatik.uni-freiburg.de>
Sent: Friday, February 18, 2000 1:39 PM
Subject: Re: [OpenBIOS] Video


> "Ronald G. Minnich" wrote:
> > My question to you: if I enable the address/IO bits to enable 'VGA', and
> > then I do VGA-style commands to the card, will the card initialize or
sit
> > there and do nothing?
> >
> > Is there really no way short of calling the video bios to init the card?
>
> Each video card has a _lot_ of knowledge stored in the video BIOS.
>
> When a card is made, an OEM takes a video chip and sticks it on their
> board.  The only way for the chip to know how to correctly access board
> memory, and other crucial details, are stored in the video BIOS.
>
> The rule is:  if you do not init video BIOS, then you must init the
> video on a per-chipset basis (ie. no generic VGA)
>
>
> > Next question then: what's the offset in video bios of the init routine,
> > or how do you find it, and what's it expect? working stack? return
address
> > in bx? Does it walk the PCI bus to find itself, and then init itself?
what
> > should I expect?
>
> Read the PCI spec on ROMs.  Basically it can be an x86 code image, Open
> Firmware code image, or something else.
>
> You will always have the problem of having to deal with x86 code images
> in expansion ROMs.  Video BIOS is only one example.
>
> --
> Jeff Garzik         | The ultimate Windows 98 keyboard:
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