Context Switch Problem

Samuel Bitton S.Bitton at sstl.co.uk
Fri May 12 15:32:50 UTC 2006


Note that I'm relying mostly on the default RTEMS configuration.
My application (which is a simple single init task that toggles a line indefinitely) only defines the following before including confdefs.h
#define CONFIGURE_TERMIOS_DISABLED
#define CONFIGURE_MAXIMUM_TASKS            2
#define CONFIGURE_RTEMS_INIT_TASKS_TABLE

Is there anything I'm missing in the RTEMS config or should that be ok in which case my current guess would be a bad memory mapping from my side.

Regards
Sam

 -----Original Message-----
From: 	Joel Sherrill [mailto:joel.sherrill at oarcorp.com] 
Sent:	12 May 2006 16:21
To:	Chris Johns
Cc:	Samuel Bitton; rtems-users at rtems.com
Subject:	Re: Context Switch Problem

Chris Johns wrote:

> Samuel Bitton wrote:
>
>> Hi
>>
>> I'm currently working on a new RTEMS BSP for a custom made board 
>> based around the i386ex processor.
>> The software currently breaks towards the end of RTEMS 
>> initialisation, at the point where it is doing the first context 
>> switch (_Context_Switch called at the end of 
>> _Thread_Start_multitasking).
>>
>> My application only has one small init task which toggles a line 
>> indefinitely.
>> Any idea what could be going wrong.
>> I'm using RTEMS 4.6.4.
>>
>
> Have you look over this page:
>
>  http://www.rtems.org/wiki/index.php/DebuggingHints
>
> It has some reasons a BSP can fail.
>
And the most likely reason is included there -- an interrupt is pending 
and you are taking
an exception.  The first context switch enables CPU interrupts and any 
device not in a
quiescent state will slap you here. :)

--joel

> Regards
> Chris







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