Quoting Ville Syrjälä (2017-11-23 17:50:50) > On Thu, Nov 23, 2017 at 07:46:23PM +0200, Ville Syrjälä wrote: > > On Thu, Nov 23, 2017 at 04:27:48PM +0000, Chris Wilson wrote: > > > Ironlake does support being able to saving and reloading context specific > > > registers between contexts, providing isolation of the basic GPU state > > > (as programmable by userspace). This allows userspace to assume that the > > > GPU retains their state from one batch to the next, minimising the > > > amount of state it needs to reload. > > > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > > --- > > > drivers/gpu/drm/i915/intel_engine_cs.c | 2 ++ > > > drivers/gpu/drm/i915/intel_ringbuffer.c | 7 +++++++ > > > 2 files changed, 9 insertions(+) > > > > > > diff --git a/drivers/gpu/drm/i915/intel_engine_cs.c b/drivers/gpu/drm/i915/intel_engine_cs.c > > > index fede62daf3e1..88ef00faf576 100644 > > > --- a/drivers/gpu/drm/i915/intel_engine_cs.c > > > +++ b/drivers/gpu/drm/i915/intel_engine_cs.c > > > @@ -175,6 +175,8 @@ __intel_engine_context_size(struct drm_i915_private *dev_priv, u8 class) > > > return round_up(GEN6_CXT_TOTAL_SIZE(cxt_size) * 64, > > > PAGE_SIZE); > > > case 5: > > > + cxt_size = I915_READ(CXT_SIZE); > > > + return round_up(cxt_size * 64, PAGE_SIZE); > > > > I don't think this is correct. It misses the non-pipelined 3D state, > > and the ring stuff at the start which IIRC at least SNB still > > saved even though it's not used in ring buffer mode. So I think > > this needs a 0xb added to the CXT_SIZE value. > > > > But even that doesn't really match the docs. The context image layout > > is shown to be 0x3b cachelines long, but 0xb+0x2d only gets us to > > 0x38. So it looks like CXT_SIZE is off by two for some reason. > > Oh. Actually CXT_SIZE is documented to be U5-1 on pre-SNB, so I > guess it's only off by one at most. U5-1, sounds typical of the hw engineers -- anything up to 2k which corresponds with their 2k alignment requirement and not cross the page boundary (which iirc was mentioned for gen4). -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
