Re: [PATCH 0/2] Allow partial memory mapping for cpu memory

[Daniel Vetter <daniel.vetter@ffwll.ch>]

On Fri, Aug 09, 2024 at 11:20:56AM +0100, Andi Shyti wrote:
> Hi Sima,
> 
> On Fri, Aug 09, 2024 at 10:53:38AM +0200, Daniel Vetter wrote:
> > On Wed, Aug 07, 2024 at 11:05:19AM +0100, Andi Shyti wrote:
> > > This patch series concludes on the memory mapping fixes and
> > > improvements by allowing partial memory mapping for the cpu
> > > memory as well.
> > > 
> > > The partial memory mapping by adding an object offset was
> > > implicitely included in commit 8bdd9ef7e9b1 ("drm/i915/gem: Fix
> > > Virtual Memory mapping boundaries calculation") for the gtt
> > > memory.
> > 
> > Does userspace actually care? Do we have a flag or something, so that
> > userspace can discover this?
> > 
> > Adding complexity of any kind is absolute no-go, unless there's a
> > userspace need. This also includes the gtt accidental fix.
> 
> Actually this missing functionality was initially filed as a bug
> by mesa folks. So that this patch was requested by them (Lionel
> is Cc'ed).
> 
> The tests cases that have been sent previously and I'm going to
> send again, are directly taken from mesa use cases.

Please add the relevant mesa MR to this patch then, and some relevant
explanations for how userspace detects this all and decides to use it.

Also, does xe also support this? If we only add this to i915-gem but xe
doesn't have it, it doesn't make much sense imo.
-Sima
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch