Re: amdmsr(4) to make xf86-video-geode useable of NetBSD

[Marc Balmer <mbalmer%NetBSD.org@localhost>]

Am 20.11.11 09:46, schrieb Marc Balmer:
> The X.Org xf86-video-geode driver, written form AMD Geode CPUs with
> graphics chips (e.g. some PC Engines ALIX boards), needs to access some
> MSRs (model specific registers) on the AMD Geode CPU at runtime to set
> the resolution etc.
> 
> On Linux this is done by opening a special file under /dev, then
> lseeking to the "right position" and writing to the file.  On BSD, or
> OpenBSD to be specific, a different approach had been choosen:  I wrote
> a small driver, amdmsr(4) (which btw autoconfigures and attaches only on
> AMD Geode CPUs) which allows access to the MSRs via ioctl(2) calls.
> xf86-video-geode driver supports this upstream.
> 
> Since I (again) have a need for small devce running X, I want to add
> amdmsr(4) to src/ and xf86-video-geode to xsrc/.
> 
> Doing it this way will also keep the xf86-video-geode driver
> maintainable, since it's compatible with the other BSD that uses this
> technique.

Here is a link to the manual page:

http://www.openbsd.org/cgi-bin/man.cgi?query=amdmsr&apropos=0&sektion=0&manpath=OpenBSD+Current&arch=i386&format=html

And here to the actual implementation in OpenBSD:

http://www.openbsd.org/cgi-bin/cvsweb/~checkout~/src/sys/arch/i386/i386/amdmsr.c?rev=1.9;content-type=text%2Fplain