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

[abssorb]

Users are still exposed to this bug.

That the bug is fixed in the repo isn't going to help people as
memtest86 is run from a liveCD or Live USB.

The buggy version is still in the download for 12.10, even though it's fixed in the repo.   It's also in the 12.10 secure remix.
Confirmed: I downloaded 12.10 64 bit today. Memtest86+ is v4.20.  The Test #7 fails with good memory- false positive.

Recommend the downloads should also contain the fix and perhaps amend
fix status to be more helpful?

People are going to get a fresh download, create a bootable CD or
LiveUSB directly from the download without involving the repo -  and get
the false positives.

I have a problem with a machine and I've spent many hours running tests
- I'd read about this bug, saw the the "fix released" status and
initially eliminated it as a problem in my investigations.  I'm sure
others will do this also and assume fix released means it's in the
latest downloads.

Even if you use the principle of RTFM, a false status against a false
positive will be a headache to work around.

My impact is I have a new machine and I made the supplier send me 4x 8Gb
RAM replacements which weren't actually needed, plus 26 hours testing
time wasted.  I would spare others that pain if I could.

With my MB / RAM config I'm getting the false positive with every ram
stick in any slot, so if I can help with further testing I'd be happy
to.

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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:
  Incomplete
Status in “memtest86+” package in Ubuntu:
  Fix Released
Status in “memtest86+” source package in Quantal:
  Fix Released
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

  --

  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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