[Intel-gfx] [PATCH] drm/i915/lmem: add the fake lmem region

[Chris Wilson]

Quoting Arkadiusz Hiler (2019-11-06 08:30:37)
> On Tue, Nov 05, 2019 at 01:05:20PM +0000, Matthew Auld wrote:
> > On Thu, 31 Oct 2019 at 20:40, Chris Wilson <chris at chris-wilson.co.uk> wrote:
> > >
> > > Quoting Arkadiusz Hiler (2019-10-31 12:40:35)
> > > > On Wed, Oct 30, 2019 at 10:22:37PM +0000, Matthew Auld wrote:
> > > > > On Tue, 29 Oct 2019 at 16:51, Matthew Auld <matthew.auld at intel.com> wrote:
> > > > > >
> > > > > > Intended for upstream testing so that we can still exercise the LMEM
> > > > > > plumbing and !i915_ggtt_has_aperture paths. Smoke tested on Skull Canyon
> > > > > > device. This works by allocating an intel_memory_region for a reserved
> > > > > > portion of system memory, which we treat like LMEM. For the LMEMBAR we
> > > > > > steal the aperture and 1:1 it map to the stolen region.
> > > > > >
> > > > > > To enable simply set the i915 modparam fake_lmem_start= on the kernel
> > > > > > cmdline with the start of reserved region(see memmap=). The size of the
> > > > > > region we can use is determined by the size of the mappable aperture, so
> > > > > > the size of reserved region should be >= mappable_end. For now we only
> > > > > > enable for the selftests. Depends on CONFIG_DRM_I915_UNSTABLE being
> > > > > > enabled.
> > > > > >
> > > > > > eg. memmap=2G$16G i915.fake_lmem_start=0x400000000
> > > > >
> > > > > Hi Arek,
> > > > >
> > > > > Would you be able to update the fi-skl-lmem kernel cmd line with
> > > > > s/i915_fake_lmem_start/i915.fake_lmem_start?
> > > >
> > > > done
> > >
> > > <6>[  497.897456] [drm] Intel graphics fake LMEM: [mem 0x100000000-0x13fffffff]
> > > <6>[  497.897459] [drm] Intel graphics fake LMEM IO start: 40000000
> > > <6>[  497.897461] [drm] Intel graphics fake LMEM size: 40000000
> > >
> > > All present.
> > 
> > Arek,
> > 
> > Could we enable DRM_I915_UNSTABLE_FAKE_LMEM in CI? That should give us
> > some coverage of the fake local-memory setup on fi-skl-lmem.
> 
> Hey,
> 
>   config DRM_I915_UNSTABLE
>           bool "Enable unstable API for early prototype development"
>           depends on EXPERT
>           depends on STAGING
>           depends on BROKEN # should never be enabled by distros!
> 
>   config DRM_I915_UNSTABLE_FAKE_LMEM
>           bool "Enable the experimental fake lmem"
>           depends on DRM_I915_UNSTABLE
> 
> AFAIU because of that dependency on CONFIG_BROKEN we cannot just enable
> it through .config - we have to edit the value in init/Kconfig[0].

Before the revert last night, CONFIG_BROKEN was already enabled in
CI. It's now enabled again. The above output was from CI setting up lmem
without extra hackery.
-Chris