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

[Robert Foss]

On 2018-06-14 04:54, Tomasz Figa wrote:
> 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.

drm_gralloc in aosp/master uses the "gralloc.drm.device" property.

> 
> Best regards,
> Tomasz
>