[Bug 1187189] Re: Kernel crash and reboot when accessing video device

[Steve Langasek]

Apparently I missed something in the changelog; but this workaround to
lxc-android-config has been uploaded.  Changelog entry:

lxc-android-config (0.14) saucy; urgency=low

  * Add diversions for /lib/udev/rules.d/50-firmware.rules and
    /lib/udev/rules.d/60-persistent-v4l.rules: the first because all of
    our firmware currently lives where only ueventd sees it (meaning udev
    will return false-negatives for firmware load requests), the second
    because even with the firmware loading out of the way, v4l_id probes
    of video devices are causing kernel panics immediately after boot
    (on mako) due to udev starting earlier than ueventd.  This works around
    LP: 1187189.

 -- Steve Langasek <steve.langasek at ubuntu.com>  Thu, 06 Jun 2013
10:39:18 -0700


** Changed in: lxc-android-config (Ubuntu)
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/1187189

Title:
  Kernel crash and reboot when accessing video device

Status in “linux-mako” package in Ubuntu:
  Confirmed
Status in “lxc-android-config” package in Ubuntu:
  Fix Released
Status in “systemd” package in Ubuntu:
  New

Bug description:
  While working on the container flip, we noticed that starting udev and
  calling udevadm trigger would cause the device to reboot instantly.

  After some effort, we tracked this down to video4linux and
  specifically the 60-persistent-v4l rules file. Looking into it, we see
  it's calling v4l_id and that's what's causing the reboot.

  Here's some basic reproducing step for saucy post-container flip:
  root at android:/ # mv /lib/udev/rules.d/60-persistent-v4l.rules /root
  root at android:/ # start udev
  udev start/running, process 1016
  root at android:/ # start udevtrigger                                             
  udevtrigger stop/waiting
  root at android:/ # cat /dev/video38
  --- reboot ---

  It looks like any attempt to open the video device causes the panic
  and reboot.

  Unfortunately I don't have any way to get a console or any kernel
  debug information so all I can tell is that there's something very
  wrong going with that video device.

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