[Intel-gfx] [PATCH] drm/i915: Add OACONTROL to the command parser register whitelist.

[Kenneth Graunke]

On 03/27/2014 01:16 PM, Daniel Vetter wrote:
> On Thu, Mar 27, 2014 at 4:57 PM, Volkin, Bradley D
> <bradley.d.volkin at intel.com> wrote:
>> On Thu, Mar 27, 2014 at 12:57:21AM -0700, Daniel Vetter wrote:
>>> Another one that blows is igt/gen7_forcewake_mt. Not sure yet whether it's
>>> an issue with the test or the checker:
>>>
>>> https://bugs.freedesktop.org/show_bug.cgi?id=76670
>>
>> For this one, the parser rejects an MI_STORE_REGISTER_MEM with the GGTT bit
>> set. We don't currently allow that, even from master. It sounds like there
>> might be released versions of the ddx that do this as well. If that's the
>> case, or if there are other situations where tests, etc rely on being able
>> to do whatever they want when setting the I915_DISPATCH_SECURE flag, then I
>> think we might as well stop parsing secure batches and let them go through
>> as before.
> 
> Well for the testcase I think we can just add the missing flag. If
> there's indeed shipping userspace out there which is getting these
> flags wrong then I think we need to silently upgrade them when copying
> the cmds over to the 2nd batch. But I guess until that need is really
> established we can hope we don't need this.
> -Daniel

Why are we parsing batches with I915_EXEC_SECURE at all?  Secure batches
are only issued from trusted code which is guaranteed to be running as
root.  I don't see any benefit to scanning those batches, and there's
definitely overhead.

I mean, sure, it may be reasonable in the short term as a way to test
the command parser, but I certainly hope we don't *ship* that.

--Ken

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