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Date: Mon, 27 Jun 2011 12:53:22 +0200
From: Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>
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Subject: Re: [Xenomai-help] Program hangs using "rt_task_sleep" in a
 particular way
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To: Adrien LEMAITRE <adrien.lemaitre@domain.hid>
Cc: xenomai@xenomai.org

On 06/27/2011 08:31 AM, Adrien LEMAITRE wrote:
> Hello,
> 
> I raise a problem encountered and always present. Before on this configuration
> :
> 
> - linux kernel : 2.6.29.6
> - adeos patch : adeos-ipipe-2.6.29-arm-1.13-00.patch
> - xenomai : 2.4.8
> - host linux distribution : ubuntu 10.04 (64 bits)
> - compiler : gcc 4.2.1 (buildroot's generated toolchain)
> 
> And it is always present with this configuration :
> 
> - Linux kernel : 2.6.37
> - Adeos patch : adeos-ipipe-2.6.37-x86-2.9-00.patch
> - Xenomai : 2.5.6
> - Host Linux distribution : Ubuntu 10.04
> - Compiler : gcc-4.4.3
> 
> Configuration of kernel:
> 
> I used the default configuration of Ubunut 10.04 and i change this:
> In "Power management and ACPI options" :
> - deactivate ACPI

This is a bad idea. Only ACPI_PROCESSOR is problematic. See:
http://www.xenomai.org/index.php/Configuring_x86_kernels

> - deactivate CPU idle PM support
> In "Device drivers/Input device support/Miscelaneous devices":
> - deactivate PC Speaker support
> In "Processor type and features":

You should only need this if you have mis-configured your kernel. Again,
see the "Processor type" paragraph in the Configuring_x86_kernels page.

> - deactivate HPET_TIMER
> - deactivate Enable -fstack-protector buffer overflow detection
> (EXPERIMENTAL)
> 
> 
> We encounter a problem in a particular situation. In the attached
> source, when we change the value passed to rt_task_sleep (line 36), the
> program never returns.
> 
> This appears only with values greater or equal to 100000 (and maybe some
> other values between 10000 and 100000) and only when we use
> rt_task_sleep between the two rt_task_spawn calls.
> 
> Is there something we've done wrong ? A problem with the kernel
> configuration? Or a bug of Xenomai ?

The real-time task are using 100% cpu time. You can not do that. A
real-time task should suspend from time to time and let non real-time
activities run.

-- 
                                                                Gilles.