From: Eric Anholt <eric@anholt.net>
To: Alan Cox <alan@lxorguk.ukuu.org.uk>,
Chris Wilson <chris@chris-wilson.co.uk>
Cc: "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>
Subject: Re: Questions about libdrm_intel and way to share physical memory between CPU and GPU
Date: Fri, 03 Jun 2011 20:32:09 -0700 [thread overview]
Message-ID: <8762ome0g6.fsf@eliezer.anholt.net> (raw)
In-Reply-To: <20110602194203.7a72ea60@lxorguk.ukuu.org.uk>
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On Thu, 2 Jun 2011 19:42:03 +0100, Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:
> On Sat, 28 May 2011 09:54:01 +0100
> Chris Wilson <chris@chris-wilson.co.uk> wrote:
>
> > On Fri, 27 May 2011 14:37:45 -0700, "Segovia, Benjamin" <benjamin.segovia@intel.com> wrote:
> > > Hello gurus,
> > >
> > > I have two question mostly regarding libdrm_intel
> > >
> > > 1/ What is the difference between drm_intel_bo_map and drm_intel_gem_bo_map_gtt ?
> > bo_map uses the CPU domain, and so is CPU linear (needs sw detiling).
> > bo_gtt_map uses the uncached [WC] GTT domain, and so is GPU linear
> > (detiling is performed by the hardware using a fence).
> >
> > > 2/ Will it be possible (or is it already possible) to directly share a regularly allocated piece of physical memory? Typical use case is the following one using OpenCL API:
> >
> > Yes. I've proposed a vmap interface to bind user-pages into the GTT,
> > similar to a completely unused bit of TTM functionality.
>
> It seems to me that stolen memory and other things could all be sorted
> out somewhat if the GEM layer and GEM as shmemfs backing were split apart
> a bit. A 'privately backed' GEM object wouldn't be able to support
> flink() but I can't find much else that would break ?
>
> Wondering about this for things like the GMA500, and also to get back all
> that memory the i9xx driver burns on a PC.
I'd much rather be able to just hand that memory off to the kernel to
use along with everything else and have there be nothing magic about it.
But as I recall, the mtrr mappings of that memory was often goofy, so it
may take some work to clean it up.
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next prev parent reply other threads:[~2011-06-04 3:32 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-27 21:37 Questions about libdrm_intel and way to share physical memory between CPU and GPU Segovia, Benjamin
2011-05-28 8:54 ` Chris Wilson
2011-05-31 23:14 ` Segovia, Benjamin
2011-06-02 18:42 ` Alan Cox
2011-06-04 3:32 ` Eric Anholt [this message]
2011-06-04 10:00 ` Alan Cox
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