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.