XGI DRM driver as a practice?

[Thomas Zimmermann]

Hi

Am 25.08.19 um 13:25 schrieb Ivan D:
> I'd like to learn DRM subsystem and GPU driver development and I was
> thinking about about writing XGI DRM driver as a practice project
> since:
> - there's (or was until recently) staging fbdev driver that should
> hopefully be working
> - it's still possible to buy thin client HW with XGI Z11 running Linux
> 
> Does it make sense at all?

That makes s lot of sense. However there are two different lines of XGI
hardware: one is SiS-based and the other is Trident-based. Those are
incompatible AFAIK. The Z11 is based on the SiS design. [1] Anything
that is Trident-based would require a different driver.


> I do have kernel experience but know very
> little about DRM and graphics. One issue is absence of documentation,
> but there could be as well others I'm not even aware of.

For documentation on VGA graphics you can read [2] and [3]. There's
kernel documentation at [4], although it lacks good tutorials on the
interfaces and the overall design.

The best way for learning about DRM is to read an existing driver. For
XGI, I'd start with bochs. It's for qemu, so you already have the
"testing hardware" as part of your Linux distribution. Bochs uses
dedicated video memory and provides atomic mode setting. That's all you
should need for a basic XGI driver.

Best regards
Thomas


[1] https://en.wikipedia.org/wiki/XGI_Technology#Cards
[2] https://wiki.osdev.org/VGA_Hardware
[3] http://www.osdever.net/FreeVGA/home.htm
[4] https://www.kernel.org/doc/html/latest/gpu/index.html

> If there's a better approach than this please drop me a line>
> Also putting relevant people from commit log to CC, hope it's ok.
> 
> Thanks,
> Ivan
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> dri-devel at lists.freedesktop.org
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> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Linux GmbH, Maxfeldstrasse 5, 90409 Nuernberg, Germany
GF: Felix Imendörffer, Mary Higgins, Sri Rasiah
HRB 21284 (AG Nürnberg)