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From: David Herrmann <dh.herrmann@gmail.com>
Date: Sat, 26 Nov 2016 19:22:15 +0100
Message-ID: <CANq1E4Rx65TVBvD8ajkRW2nk4b-1AsP_7T2cuJ7TpcYQu+O4Sg@mail.gmail.com>
Subject: Re: drm: GPF in drm_getcap
To: Dmitry Vyukov <dvyukov@google.com>
Cc: syzkaller <syzkaller@googlegroups.com>,
        Daniel Vetter <daniel.vetter@ffwll.ch>,
        David Airlie <airlied@linux.ie>,
        "dri-devel@lists.freedesktop.org" <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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Hi

On Sat, Nov 26, 2016 at 7:07 PM, Dmitry Vyukov <dvyukov@google.com> wrote:
> grep "card0" dmesg:
> [    5.298617] device: 'card0': device_add
> [    5.298946] PM: Adding info for No Bus:card0
> [    6.436178] device: 'card0': device_add
> [    6.436488] PM: Adding info for No Bus:card0
>
>
> # ls -l /dev/dri/card0
> crw-rw---T 1 root video 226, 0 Nov 26 18:05 /dev/dri/card0
>
> # ls -lt /sys/class/drm/card0/device/
> ls: cannot access /sys/class/drm/card0/device/: No such file or directory
>
> # ls -lt /sys/class/drm/card0/device/driver
> ls: cannot access /sys/class/drm/card0/device/driver: No such file or directory

Looks like vgem. Something like this should help:

    https://gist.github.com/dvdhrm/1bcdf4f3485aa1614a0198a7b90515e2

I wonder whether it would be more appropriate to return -ENOTSUPP rather than 0.

Thanks
David