suggested xorg-compatible video HW for FreeBSD/amd64 ?

Jung-uk Kim jkim at FreeBSD.org
Tue Nov 29 20:18:12 UTC 2011


On Tuesday 29 November 2011 02:18 pm, Adam K Kirchhoff wrote:
> On 11/29/11 14:12, Jung-uk Kim wrote:
> > On Tuesday 29 November 2011 01:36 pm, Adam K Kirchhoff wrote:
> >> On 11/29/11 13:19, Adam K Kirchhoff wrote:
> >>> On 11/29/11 13:04, Jung-uk Kim wrote:
> >>>> I believe major hurdle is porting TTM but the future of this
> >>>> API is not so bright.  In fact, X.org ATI driver uses GEM API
> >>>> now and it is internally mapped to TTM calls by Linux DRM (aka
> >>>> "GEM-ified TTM manager").  Unfortunately, as always, I don't
> >>>> see clear plans from Linux/X.org developers.  I can only guess
> >>>> few possibilities.
> >>>>
> >>>> 1. Linux/X.org folks drop GEM-ified TTM and use native GEM
> >>>> calls. 2. Linux/X.org folks drop GEM-ified TTM and use native
> >>>> TTM calls. 3. Linux/X.org folks re-invent new wheels (again).
> >>>> 4. No change.
> >>>>
> >>>> My guess is #1 is most likely scenario in the near future. 
> >>>> Even if Linux/X.org folks don't do it, we may be able to
> >>>> implement it without TTM because X.org ATI driver uses GEM API
> >>>> already and we do not have AMD/ATI Catalyst driver for FreeBSD
> >>>> anyway.  So, I guess we have two choices ATM:
> >>>>
> >>>> 1. Fully porting TTM, GEM-ified TTM, and KMS.
> >>>> 2. Replacing GEM-ified TTM with GEM and porting KMS.
> >>>>
> >>>> BTW, I am not volunteering. ;-)
> >>>>
> >>>> Jung-uk Kim
> >>>> _______________________
> >>>
> >>> Every conversation I've had with the radeon driver developers
> >>> on the matter, even quite recently, has led me to believe that
> >>> TTM will not be going away.  GEM is only appropriate for IGP
> >>> GPUs. Unless that changes within GEM, I do believe TTM will be
> >>> used internally on the radeon DRM indefinitely.
> >>>
> >>> If I had to guess, I'd say that anyone on the FreeBSD side
> >>> deciding to get rid of TTM and use GEM only GEM for radeons
> >>> would eventually come to the same conclusion as the developers
> >>> who have been working with radeon hardware for years :-)
> >>
> >> Correction.  GEM seems to be focused on Intel IGP GPUs. 
> >> According to one of the radeon developers on #radeon on
> >> freenode, even radeon IGP GPUs need something like TTM.
> >>
> >> Honestly, I'm wondering how you came to the conclusion that
> >> future of TTM is not so bright... ? :-)
> >
> > I know it was developed for Intel IGPs (by anholt@, former
> > FreeBSD DRM maintainer).  However, I was under (wrong?)
> > impression that xf86-video-ati is using GEM API because it wasn't
> > absolutely necessary.  AFAIK, Nouveau folks also did something
> > similar, OpenChrome guys are doing the same thing, etc.  If TTM
> > is really necessary, why "GEM on TTM" hack in the first place?
>
> It is my understanding that to simplify have one unified API for
> interacting with the DRM code, the radeon developers (and others)
> agreed/decided to use the GEM userspace API, even though the
> internals (for radeon DRM) require functionality provided by TTM.

Understood.

> For what it's worth, the radeon developer I just spoke to even said
> in order to remove TTM from the equation, "something" would have to
> be recoded to do "partly what ttm does".

Yes, *partly*.  That's exactly what I was talking about.  If porting 
entire TTM layer is harder than recoding to do "partly what TTM 
does", then it is worth considering, IMHO.

Jung-uk Kim


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