gcc 4.2.4 TIMER_ABSOLUTE failure

[Gertjan]

Binary package hint: gcc-4.2

POSIX timer TIMER_ABSOLUTE fails under GDB. This appears only to be a problem with Ubuntu, not with other distrubutions and/or versions of GCC.
The problem was first thought to be a bug with the High Resolution Timers in the kernel. With some help from Mr. T. Gleixner, we determined the problem really only occurs with the Ubuntu build of GCC. The issue is described in detail in http://bugzilla.kernel.org/show_bug.cgi?id=12157

Essentially, Ubuntu gcc 4.2 compiled programs fail to return from the high timer call when running under GDB. This is not a problem when a pre-compiled Debian kernel is run with an Ubuntu 8.04.1 distribution. It is also not a problem when the Ubuntu 2.6.24 kernel is re-compiled with gcc 3.4.

Please see the kernel bug reference for further details. I would be happy to do some trials if needed.

Sincerely

Gertjan Hofman

[Colin Watson (cjwatson)]

In the kernel bug report, you quote gcc-4.2 4.2.3-2ubuntu7, but in this report you say gcc 4.2.4. Could you clarify exactly which package version you're using, as there have been several updates fixing code generation bugs throughout the lifetime of Ubuntu 8.04?

  dpkg-query -W gcc-4.2

[Gertjan (gertjan-hofman)]

Colin,

Sorry - it might have been the available selection. The package on my systems is:

ghofman@evolution05:~> dpkg-query -W gcc-4.2
gcc-4.2 4.2.4-1ubuntu3

ghofman@evolution05:~> gcc --version
gcc (GCC) 4.2.4 (Ubuntu 4.2.4-1ubuntu3)

Thanks for taking an interest. I am surprised this is not known - the combination of POSIX timers and gdb cant be that uncommon.

Gertjan

[Matthias Klose (doko)]

marking it as won't fix for gcc-4.2 (which was removed in lucid).

Gertjan, please could you open a new task for gcc-4.4 in this report, if it's still reproducible in lucid?

[Gertjan (gertjan-hofman)]

Matthias,

A quick test of the code from https://bugzilla.kernel.org/show_bug.cgi?id=7967
showed everything is fine under Lucid.

Cheers

Gertjan

--- On Thu, 6/10/10, Matthias Klose <email address hidden> wrote:

> From: Matthias Klose <email address hidden>
> Subject: [Bug 313292] Re: gcc 4.2.4 TIMER_ABSOLUTE failure
> To: <email address hidden>
> Received: Thursday, June 10, 2010, 6:35 AM
> marking it as won't fix for gcc-4.2
> (which was removed in lucid).
>
> Gertjan, please could you open a new task for gcc-4.4 in
> this report, if
> it's still reproducible in lucid?
>
>
> ** Changed in: gcc-4.2 (Ubuntu)
>        Status: New => Won't
> Fix
>
> --
> gcc 4.2.4 TIMER_ABSOLUTE failure
> https://bugs.launchpad.net/bugs/313292
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