[Xorg-driver-geode] Questions for FreeBSD build.

[Jordan Crouse]

On 19/12/07 18:33 -0800, Larry Maloney wrote:
> Jordan,
>
> OK, I have a batch of questions.
>
> #1) In the ports collection for FreeBSD  there is an existing 
> xf86-video-nsc driver.  I believe this is the National Semiconductor Video 
> driver.
>
>    a.) Will this driver work with the GEODE video?

No - it doesn't support the GX/LX, only the GX1 and single chip processors.
A merger has been discussed, but not finalized.

>    b.) If not, would this be the best driver make/config to start with.

No, because it doesn't support your hardware.  Though we should have nearly
identical configuration scripts  - if not, let me know, and we need to do some
comparisons.

>
> #2.) The AMD Geode drivers have a file called z4l.c  This file appears to 
> be for Video For Linux.  If I were to omit this file from the build 
> enviornment
>       would the drivers work?  (Granted Video for Linux would be disabled)

Yes - the graphics drivers will work just fine.  Personally, I have little
use for the z4l.c driver - I think that in most cases, you are better off
using a well known pipeline between V4L and Xv (such as gstreamer).  

> #3.) I can get stock VGA drivers to run, however, the VGA driver believes 
> that there is only 64K ram of video on the card. I doubled checked the BIOS 
> and it's set to 16MB.

>        One possible problem might be that I disabled EISA in my kernel 
> build.  I will turn that back on.  Any other ideas why only 64KB is seen by 
> the VGA driver?

There are several reasons, and they all have to do with legacy.
The VGA graphics framebuffer is at most 640x480-16 (64k), which is mapped
at physical address 0xa0000 in the x86 physical memory space for legacy
reasons.  The Geode has built in VGA glue that helps map the legacy 
space into the real video memory.  Together with the video BIOS, the 
effect is seamless, and the VGA driver only sees what it is supposed to -
64k of framebuffer memory.

When you turn off VGA, then control returns to the GPU, and you will have
access to the full extent of your video memory through the PCI device.

Jordan

-- 
Jordan Crouse
Systems Software Development Engineer 
Advanced Micro Devices, Inc.