Test your agp(4) before blaming on DRM/DRI!
Scott Long
scottl at freebsd.org
Fri May 21 01:09:35 PDT 2004
Jung-uk Kim wrote:
> I was trying to make my Intel i815 and VIA K8T800 chipsets working
> with agp(4) and I found that there were number of issues in the
> driver. These issues were mainly from adding PCI IDs blindly without
> verifying proper documentation. On top of that, some drivers do not
> care whether the bridge is supported or not and just attach as
> 'generic' bridge, e. g., agp_sis.c and agp_via.c. This gives users
> false hope and I believe this is wrong.
>
> I found the following from DRI website:
>
> http://dri.sourceforge.net/res/testgart.c
>
> and SuSE Linux had little newer package:
>
> http://www.suse.de/us/private/products/suse_linux/prof/packages_professional/testgart.html
>
> I modified SuSE's to work with FreeBSD. Test your GART before blaming
> on DRM/DRI! If aperture size is reported differently from BIOS
> setting, that is not supported correctly, e. g., i815 - different
> aperture size encoding and registers. If writeback test fails,
> that's more serious problem, e. g., K8T800 - doesn't work at all for
> me.
>
> BTW, you have to unload your drm driver (or recompile kernel if you
> compiled it in) before you test agp.
>
> I hope this helps many confused users.
>
> Cheers,
>
> Jung-uk Kim
>
>
> * PS: Is there anybody working on AMD64 on-CPU GART driver like this?
>
> http://fxr.watson.org/fxr/source/drivers/char/agp/amd64-agp.c?v=linux-2.6.1
>
> Documentation is here (Section 3.6.11-14):
>
> http://www.amd.com/us-en/assets/content_type/white_papers_and_tech_docs/26094.PDF
There has been talk about adding support for this into the busdma
framework. Another nice TODO item if anyone wants it.
Scott
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