Re: [PATCH v2 17/18] drm/i915: Wa32bitGeneralStateOffset & Wa32bitInstructionBaseOffset

Chris Wilson
2015-06-18T07:34:18Z

On Thu, Jun 18, 2015 at 09:11:46AM +0200, Daniel Vetter wrote:
> I've been dense, somehow I thought we need the execbuf opt-in with the
> object opt-out. But opt-in at the object level is indeed all we need.

To be fair and recap our discussion on irc, the other side of the coin
is that at some point we want to use 48bit by default (gen9, gen10,
whenever it is robust!) Daniel's argument is that with an high level
enable bit + opt-out, there is less work in userspace to dtrt.

Imo, having changed userspace to opt-in when possible with gen8, having
userspace opt-in for all objects is then trivial (plus it is then easier
for userspace to disable it again). Having a flag at the execbuf level
would be nice, but given the changes we need in userspace today (to
support either the opt-in/opt-out model), I think a second flag is of no
practical value.
-Chris

--
Chris Wilson, Intel Open Source Technology Centre