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Re: Getting spurious FAILS in testsuite?

On 08.06.2017 23:33, Andrew Pinski wrote:
On Thu, Jun 8, 2017 at 2:25 PM, Jeff Law <> wrote:
On 06/08/2017 04:24 AM, Christophe Lyon wrote:
On 8 June 2017 at 11:57, Georg-Johann Lay <> wrote:
On 05.06.2017 18:25, Jim Wilson wrote:

On 06/01/2017 05:59 AM, Georg-Johann Lay wrote:

Hi, when I am running the gcc testsuite in $builddir/gcc then
$ make check-gcc RUNTESTFLAGS='ubsan.exp'
comes up with spurious fails.

This was discussed before, and the suspicion was that it was a linux
kernel bug.  There were multiple kernel fixes pointed at, it wasn't
clear which one was required to fix it.

I have Ubuntu 16.04 LTS on my laptop, and I see the problem.  I can't
run the ubsan testsuites with -j factor greater than one and get
reproducible results.  There may also be other ways to trigger the

See for instance the thread
The first message in the thread from Andrew Pinski mentions that the log
output is corrupted from apparent buffer overflow.


I have "Ubuntu 16.04.2 LTS".

Asking this at DejaGNU's, I got the following pointer:

AFAIU there is a problem separating stdout and stderr?

Be careful, I'm not a dejagnu maintainer/developer :-)
I just meant to say I had "similar" problems, but according to this
thread, I'm not the only one :(
There was most definitely a linux kernel bug that affected the behavior
of "expect" used by dejagnu in the past.

THe reference to a message from Pinski is the right one --
it identifies the problematical change in the kernel that mucked up
expect's behavior.

In the thread you'll find a reference to:

This has long since been fixed.  BUt I have no idea what version of hte
kernel is in Ubuntu and whether or not it is subject to this problem.

I think 4.10 or 4.11 has the full fix.  There was still some bugs even
in 4.8 (which was the one included with Ubuntu 1604).  I only say this
is because I have a 4.8 kernel which sees the problem but a 4.11
kernel does not.  The behavior I see with a non fixed kernel is that
the guailty tests will not run at all.  With the fixed kernel, it will


FYI, I am on 4.11.2 now and the spurious FAILs persist.

$ uname -a
Linux 4.11.2-041102-generic #201705201036 SMP ... x86_64 GNU/Linux

$ lsb_release -dicr
Distributor ID: Ubuntu
Description:    Ubuntu 16.04.2 LTS
Release:        16.04
Codename:       xenial


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