[OpenBIOS] Video

[Ronald G. Minnich]

ah, such fun. Jeff, can you tell me more. 

On Fri, 18 Feb 2000, Jeff Garzik wrote:

> VGA is the standard, that is why it is popular.  Linux text mode console
> works because VGA works on most PCs.  Executing video BIOS is an
> absolute requirement to supporting VGA in a generic fashion.

Let's take the L440GX (please! :-). I want video on it to act like VGA. 

On this board you've got to set some things in PCI config registers to
enable 'VGA mode'. These are for such things are mapping of 0xa0000 space,
MDA space, which out/in instructions go to the card, and so on. 

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? 

If it's true there's no other way, well, I'm not completely screwed for
cluster use, but it's still bad for everyone else.

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? 

If I can't init video from open source I'll put this one on the back
burner for now and do it later. But we've got to deal with this at some
point. 

Also recall that there used to be similar arguments about things like disk
and ethernet controllers. The decision in the open source community is to
support what you can, and not try to do everything. People who really want
you to support their card will come around eventually. Intel once made me
sign a five-year NDA on the pro-100a network card; five months later they
were giving the docs away to anyone willing to write a driver for *bsd or
linux. They learned.

ron 

p.s. true story: someone at a famous research lab once wrote a 386
simulator, just so he could figure out how to init a graphics card. He
booted dos on his simulator and waited for the graphics card init to run,
at which point he stopped worrying about his simulator :-) Took about a
day or two, but he said it was worth it :-)

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