Non-x86 Video

Stefan Reinauer stepan at
Mon May 3 15:09:01 CEST 2004

* Bari Ari <bari at> [040503 22:15]:
> You need the videoBIOS when you first init the device after reset unless 
> you wish to come up with all your own (possibly several hundred) 
> register values.

Going the direct way by programming registers is a lost game for
every component that is not onboard (And it even does not make all that
much sense for all onboard hardware)

> You may use the videoBIOS when you wish to change the video mode but you 
> may also do it with your own set of register values on the fly.
LinuxBIOS+x86 emulation should set an initial mode that can be used
later on by the operating system (vesafb basically works like this, too)

> XFree86 drivers sometimes rely on the videoBIOS, sometimes not.
If they do, and you are on a non-x86 platform, they are basically using
the same x86 emulation core that LinuxBIOS uses: x86emu. 

> I know this is going beyond Ron's plan. Let's say there is source for an 
> XFree86 driver for a graphics device with all the 3-D and Zoom port 
> support. I haven't looked at the emulator yet. Using the 8086 emulator 
> would this support fb driver only? or would you also be able to support 
> XFree86 drivers compiled for ARM?

The video bios is needed in first place to get the hardware on the video
card activated. This task is very often not performed by X11. This is
why we need to initialize the card before X11 comes into play.

If there are open source drivers for X11, they should work by just
recompiling them for your target platform. Given that they are cleanly


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