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[Launchpad Bug Tracker <1209261@xxxxxxxxxxxxxxxxxx>]

[Expired for unity (Ubuntu) because there has been no activity for 60
days.]

** Changed in: unity (Ubuntu)
       Status: Incomplete => Expired

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https://bugs.launchpad.net/bugs/1209261

Title:
  unity has issues with intel gen3 hardware in 2 screens configs

Status in “unity” package in Ubuntu:
  Expired

Bug description:
  Unity in Raring has an issue with intel gen3 graphics hardware. When a
  second screen is connected (e.g. an external monitor or projector is
  connected to a laptop), unity/compiz crashes and the machine remains
  alive but almost useless.

  This makes it impossible to give presentations with a projector with
  many small laptops with intel gen3 graphics hardware.

  Using 2 screens on gen3 was possible till not long ago with unity, so
  this bug is a regression.

  The reason for the issue has already been found, here is a brief
  discussion. See also
  https://bugs.freedesktop.org/show_bug.cgi?id=67846.

  Gen 3 hardware can only support screens when the size is less than
  4096x4096.  However it can only support GL framebuffer objects as wide
  as 2048x2048.  As a matter of fact, software workaround were attempted
  to rise this to 4096x4096 but they are currently broken. This means
  that unity on two screens can be supported as long as the overall size
  of the two screens is within 2048x2048.  Fitting in that limit is by
  no means hard if the two screens are arranged one above the other with
  xrandr.  This is quite true for small laptops that often only have a
  600 pixels vertical resolution.

  Unfortunately, the latest unity tries to autoconfigure thing when a
  second screen is attached by automatically putting it on the side of
  the original screen. With this the overall size of 2048x2048 is easily
  exceeded, the GL fbo cannot be allocated and compiz crashes.

  IMHO opinion there are 2 points that should be addressed

  1) Compiz/Unity should never crash. If the GL cannot provide what is
  needed when the second screen is attached, unity should not crash, but
  in the worst case at least fall back to a single screen config,
  ignoring the external monitor, thus leaving the machine in a usable
  state

  2) When attaching a second monitor, unity should either:
  - not try to much magic. Ask the user what to do, and how to configure the screens; or
  - include a table of quirks so that it knows that certain setups are not possible and avoid them.  For instance when gen3 hardware is detected it should know that the overall size with two monitors must fall within 2048x2048 and organize the screens accordingly if possible (e.g. one above the other) or leave the external monitor unconfigured if impossible.

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