Re: [PATCH] drm/i915: Revert "drm/i915: Reject the pin ioctl on gen6+"

[Jesse Barnes <jbarnes@virtuousgeek.org>]

On Mon, 7 Jul 2014 23:04:55 +0200
Daniel Vetter <daniel@ffwll.ch> wrote:

> On Thu, Jul 03, 2014 at 08:12:35AM +0100, Damien Lespiau wrote:
> > This reverts commit 02f6bcccf7c324115747aae2f0addd6af5d321cd.
> > 
> > The OA buffer can contain global data (in particular, not linked to a
> > context or a single batch execution) about GPU events (eg. hw context
> > switches, rc6 transitions, frequency changes, ...) and needs to be
> > mapped to GGTT. The pin ioctl provided a way to do that.
> > 
> > Admittedly, this change broke what seems to be a valid use case of
> > pinning a buffer in GGTT, even when PPGTT is used (which is the reason
> > invoked in the commit message).
> 
> Global OA buffers should be handled by the kernel and exposed through
> perf, imo. I think I'll go lalala on this a bit longer ...

Why?  Because allowing the pin ioctl as root is such a problem?  You
need to come up with an alternative proposal and we need to get it
implemented in some reasonable amount of time if we're not going to
just do the simple thing that's already been shown to work...

IOW don't plug your ears and say "lalala" for too long.

-- 
Jesse Barnes, Intel Open Source Technology Center