[Bug 1247607] Re: Libdrm compiled with gcc 4.8 makes card hang on resume from s2disk

[Chris Halse Rogers]

Hello Ronald, or anyone else affected,

Accepted libdrm into precise-proposed. The package will build now and be
available at
http://launchpad.net/ubuntu/+source/libdrm/2.4.46-1ubuntu0.0.0.1 in a
few hours, and then in the -proposed repository.

Please help us by testing this new package.  See
https://wiki.ubuntu.com/Testing/EnableProposed for documentation how to
enable and use -proposed.  Your feedback will aid us getting this update
out to other Ubuntu users.

If this package fixes the bug for you, please add a comment to this bug,
mentioning the version of the package you tested, and change the tag
from verification-needed to verification-done. If it does not fix the
bug for you, please add a comment stating that, and change the tag to
verification-failed.  In either case, details of your testing will help
us make a better decision.

Further information regarding the verification process can be found at
https://wiki.ubuntu.com/QATeam/PerformingSRUVerification .  Thank you in
advance!

** Tags removed: verification-done

** Tags added: verification-needed

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https://bugs.launchpad.net/bugs/1247607

Title:
  Libdrm compiled with gcc 4.8 makes card hang on resume from s2disk

Status in The GNU Compiler Collection:
  New
Status in Accelerated Xorg driver for nVidia cards:
  Fix Released
Status in “libdrm” package in Ubuntu:
  Fix Released
Status in “libdrm” source package in Saucy:
  Fix Released

Bug description:
  [Impact] 
   * Relocations on nv04-nv4f are completely broken, any kind of memory stress will result in userspace failure.

  [Test Case]
   * Suspend on a system with an affected nvidia card.
   * Resume should complete without any errors in FIFO.
   * Other test is to run max-texture-size from piglit, system should survive.
   * For m-a same change: confirm libdrm-dev:amd64 and libdrm-dev:i386 coinstall.

  [Regression Potential] 
   * Original bug report was caused by undefined behavior in gcc:
     - *push->cur++ = pushbuf_krel(push) 
     - pushbuf_krel uses (push->cur - push->bgn) to calculate offset.
     - It's undefined whether push->cur is incremented before calling pushbuf_krel or not.
     - New gcc changed the order, causing the bug.
     - Fixed by calling push->cur++ in a separate statement.
   * Bug reports will be watched for any new problems that may pop up.

  [Original bug report]
  My initial bugreport was here: https://bugs.freedesktop.org/show_bug.cgi?id=71116

  - Recompiling libdrm with gcc 4.7 fixed the bug.

  Upstream GCC mail thread here: http://gcc.gnu.org/ml/gcc-
  help/2013-07/msg00103.html

  This was fixed thanks to Emil Velikov from the nouveau project.

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