[Bug 1071209] Re: memtest86 test #7 false positives (random number sequence error)

[Lynara Le'dominae]

This bug also affects me. Bought two new sticks of RAM, and was
suggested I test the processor to see if it was the issue... Glad I
found this out before I went any further.

Gateway ID49CU
Ubuntu 12.10

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https://bugs.launchpad.net/bugs/1071209

Title:
  memtest86 test #7 false positives (random number sequence error)

Status in Memtest86+:
  Unknown
Status in Release Notes for Ubuntu:
  New
Status in “memtest86+” package in Ubuntu:
  Fix Released
Status in “memtest86+” source package in Quantal:
  In Progress
Status in “memtest86+” source package in Raring:
  Fix Released
Status in “memtest86+” package in openSUSE:
  Fix Released

Bug description:
  Trying to check the memory at newly bought notebook I found a bug in
  the memtest86+ version 4.20 in ubuntu 12.10, in ubuntu 12.04 it is ok.
  The bug is reported at least in Fedora and Opensuse. It is assumed
  that the bug is caused by the gcc-4.7.

  It is easily  reproducible - select the test #7 in memtest or just
  wait till it - starting from the 129Mb it will report a lot of errors.
  I have checked it on three different systems , two of them I use on a
  daily basis and would note if RAM is really bad.

  https://bugzilla.redhat.com/show_bug.cgi?id=805813

  http://lists.opensuse.org/opensuse-bugs/2012-09/msg04386.html

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  SRU Justification

  [Impact]
  Users of memtest86+ will get false positives of memory failures. This will cause users to suspect hardware and require unnecessary testing/headaches.

  [Test Case]
  Boot Ubuntu in Quantal/Raring. At GRUB select memtest86+. Wait until the 7th test. It will fail at the 7th test.

  [Regression Potential]
  The fix is just adding another register to clobber in the inline assembly routine. Because  this affects newer GCC versions, older releases aren't affected. Thus, if there are compiler changes we should re-test.

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