[Mesa-dev] [PATCH v3 3/3] egl/android: Add DRM node probing and filtering

[Tomasz Figa]

On Thu, Jun 14, 2018 at 4:14 AM Rob Herring <robh at kernel.org> wrote:
>
> On Wed, Jun 13, 2018 at 12:19 PM, Amit Pundir <amit.pundir at linaro.org> wrote:
> > On 13 June 2018 at 20:45, Rob Herring <robh at kernel.org> wrote:
> >>
> >> +Amit and John
> >>
> >> On Sat, Jun 9, 2018 at 11:27 AM, Robert Foss <robert.foss at collabora.com> wrote:
> >> > This patch both adds support for probing & filtering DRM nodes
> >> > and switches away from using the GRALLOC_MODULE_PERFORM_GET_DRM_FD
> >> > gralloc call.
> >> >
> >> > Currently the filtering is based just on the driver name,
> >> > and the desired name is supplied using the "drm.gpu.vendor_name"
> >> > Android property.
> >>
> >> There's a potential issue with this whole approach and that is
> >> SELinux. With the way SELinux locks down accesses, getting probing
> >> thru device files to work can be a pain. It may be better now than the
> >> prior version because sysfs is not probed. I'll leave it to Amit or
> >> John to comment.
> >
> > Right.. so ICYMI, this patch is already pulled into external/mesa3d
> > project of AOSP and I stumbled upon one such /dev/dri/ access denial
> > on db820c recently.
>
> A prior version of the patch series which accesses sysfs too (via libdrm).
>
> >
> > In AOSP, zygote spawned apps already have access to GPU device nodes
> > in the form of /dev/gpu_device file, but the missing part is the
>
> It's "gpu_device" in terms a a SELinux context, right? Not an actual /dev path?
>
> > open-read access to "/dev/dri/" which need to be allowed explicitly.
>
> Or we need a way to just open a specific device.

How does this work in drm_gralloc (or any other existing gralloc that
implements GRALLOC_MODULE_PERFORM_GET_DRM_FD)? What device node does
it open? I have some loose recollection that it had a property
specifying exact device. I guess we could use that property as the top
level override, bypassing the whole probing logic, if present.

Best regards,
Tomasz