From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ville =?iso-8859-1?Q?Syrj=E4l=E4?= <ville.syrjala@linux.intel.com>
Subject: Re: [PATCH] drm/i915: Enable full PPGTT on gen7
Date: Tue, 9 Sep 2014 15:34:59 +0300
Message-ID: <20140909123459.GE4193@intel.com>
References: <1409922796-453-1-git-send-email-michel.thierry@intel.com>
 <20140909115711.GF19343@nuc-i3427.alporthouse.com>
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To: Chris Wilson <chris@chris-wilson.co.uk>, Michel Thierry <michel.thierry@intel.com>, intel-gfx@lists.freedesktop.org
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On Tue, Sep 09, 2014 at 12:57:11PM +0100, Chris Wilson wrote:
> On Fri, Sep 05, 2014 at 02:13:16PM +0100, Michel Thierry wrote:
> > Use full PPGTT as the default option in gen7.
> > Note that aliasing PPGTT is the default option for gen8 (see HAS_PPGTT).
> > =

> > This may well come back to bite me later.
> =

> Indeed. So something I spotted was that bspec mentions that the per-ring
> PDE registers (RING_PP_DIR_DCLV and RING_PP_DIR_BASE) are stored in the
> logical context and so the registers are restored along with the
> context. If this is correct what happens when we switch logical contexts
> on RCS whilst we have active work on BCS etc? Does this mean that we
> have to serialise context switches across rings, or is my reading of the
> bspec false?

How does rcs PP_DIR_* affect bcs? Also IIRC that stuff is part of
the execlist context which isn't saved/restored unless execlists
are actually enabled. IIRC when I tried it, snb did reserve the
space for that stuff in the context image but didn't save/restore
it, but ivb+ didn't even reserve the space.

-- =

Ville Syrj=E4l=E4
Intel OTC