Debugging basic BSP tasking functionality
Joel Sherrill
joel.sherrill at OARcorp.com
Wed Apr 17 15:01:29 UTC 2013
On 4/17/2013 9:47 AM, Matthew J Fletcher wrote:
> >If you put an explicit call to rtems_stack_checker_is_blown() in
> Init() at
> >various points, does it think things are OK?
>
> I put in a few and even the last one before the Init() task deletes
> itself is ok.
>
>
OK.
> >Just to be clear.. is this with the rtl22xx or rtl22xx_t BSP? The
> non-thumb version
> >uses -mapcs-frame which no other BSP uses. That makes me wonder.
>
> rtl22xx_t 'Thumb', -mapcs-frame is passed on the gcc command line.
>
If this is the BSP you are using, take it off and try again. This is the
only BSP
using this option. Sebastian can probably comment on the other arguments.
>
> >Not with RTEMS. When you enter/exit an ISR, you go through some
> >code which saves the proper registers, probably switches you to
> >a dedicated stack, and does the OS stuff needed so it will do
> >any needed dispatching at the end of the interrupt.
>
> Is this shared between BSPs ? i tried to look for this and failed.
>
>
It is absolutely shared. The BSP has to provide some glue code but
between libbsp/shared, libbsp/<ARCH>/shared, and the appropriate
libcpu directory, you will find the code.
Look for shared and libcpu in the Makefile.am.
Now as Sebastian says, the handler might be mis-registered as raw
not OS interrupt. And the BSP may have been mechanically converted
to the new shared PIC interrupt code used by many BSPs but not
tested.
>
>
> On 17 April 2013 15:34, Joel Sherrill <joel.sherrill at oarcorp.com
> <mailto:joel.sherrill at oarcorp.com>> wrote:
>
> On 4/17/2013 9:04 AM, Matthew J Fletcher wrote:
>> Hi,
>>
>> Yes it the stack pointer out of range, because the current stack
>> pointer returned by GCC _builtin_frame_XX in the IDLE thread
>> looks like its actually that from the Init() thread.
>>
> You are completely in C code when this happens. There has been
> assembly
> to switch to the task initially (e.g. into _Thread_Handler) and if
> an interrupt
> occurred.
>
> If you put an explicit call to rtems_stack_checker_is_blown() in
> Init() at
> various points, does it think things are OK?
>
> It is easy for the stack not to be initialized to match gcc or
> gdb's expectation
> of how it ends.
>
> Just to be clear.. is this with the rtl22xx or rtl22xx_t BSP? The
> non-thumb version
> uses -mapcs-frame which no other BSP uses. That makes me wonder.
>
>> Thinking this through,my target is Thumb, so the C interrupt
>> handler should be in a arm file with -mthumb-interwork set on the
>> compile line.
>>
>> I guess GCC can not auto-magicly know what particular functions
>> are interrupts, so should there be some entry/exit functions to
>> save/restore the stack, etc, like these...
>>
>> http://www.procyonengineering.com/embedded/arm/armlib/docs/html/group__processor__lpc2000.html
>>
>> ISR_ENTRY / ISR_EXIT
>>
>>
> Not with RTEMS. When you enter/exit an ISR, you go through some
> code which saves the proper registers, probably switches you to
> a dedicated stack, and does the OS stuff needed so it will do
> any needed dispatching at the end of the interrupt.
>
> --joel
>
>>
>>
>>
>>
>> On 17 April 2013 13:40, Sebastian Huber
>> <sebastian.huber at embedded-brains.de
>> <mailto:sebastian.huber at embedded-brains.de>> wrote:
>>
>> On 04/17/2013 02:27 PM, Matthew J Fletcher wrote:
>>
>> >Here a context switch from the Init to the idle (I
>> guess) thread happens.
>> The >_User_extensions_Thread_switch
>> >() is called before the context switch and the running
>> thread is checked. So
>> a sp of >0x814d299c must be in the range of the Init
>> stack area.
>>
>> Yes it is, Init() stack area is 0x814d1a70 -> 0x814d2a74
>> (4100 bytes). So it
>> looks like the stack pointer is not getting adjusted
>> correctly when task
>> switching into a new thread ? as the rtems_idle task is
>> using the Init() stack
>> pointer.
>>
>>
>> Now I am a bit confused. What check goes wrong in
>>
>>
>> Stack_check_Frame_pointer_in_range() at check.c:69 0x81180f6e
>> rtems_stack_checker_switch_extension() at check.c:276 0x81180f6e
>> _User_extensions_Thread_switch() at userextthreadswitch.c:41
>> 0x8118cbaa
>> _Thread_Dispatch() at threaddispatch.c:128 0x8118bce6
>> _Thread_Enable_dispatch() at threaddispatch.c:59 0x8118bd5e
>> rtems_task_delete() at taskdelete.c:94 0x81189750
>> Init() at startup.c:241 0x81007840
>>
>> ?
>>
>> In case the stack pointer is out of range, then I guess that
>> the interrupt exception processing is broken. It is hard to
>> know what happens without an actual target.
>>
>>
>>
>> > nm your-app.exe | grep 'bsp_\(section\|stack\)' | sort
>>
>> No matches.
>>
>>
>> Ok, 4.10 uses the old linker command files. These symbols
>> are only available in 4.11.
>>
>>
>> --
>> Sebastian Huber, embedded brains GmbH
>>
>> Address : Dornierstr. 4, D-82178 Puchheim, Germany
>> Phone : +49 89 189 47 41-16 <tel:%2B49%2089%20189%2047%2041-16>
>> Fax : +49 89 189 47 41-09 <tel:%2B49%2089%20189%2047%2041-09>
>> E-Mail : sebastian.huber at embedded-brains.de
>> <mailto:sebastian.huber at embedded-brains.de>
>> PGP : Public key available on request.
>>
>> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne
>> des EHUG.
>>
>>
>>
>>
>> --
>>
>> regards
>> ---
>> Matthew J Fletcher
>>
>
>
> --
> Joel Sherrill, Ph.D. Director of Research & Development
> joel.sherrill at OARcorp.com <mailto:joel.sherrill at OARcorp.com> On-Line Applications Research
> Ask me about RTEMS: a free RTOS Huntsville AL 35805
> Support Available (256) 722-9985
>
>
>
>
> --
>
> regards
> ---
> Matthew J Fletcher
>
--
Joel Sherrill, Ph.D. Director of Research & Development
joel.sherrill at OARcorp.com On-Line Applications Research
Ask me about RTEMS: a free RTOS Huntsville AL 35805
Support Available (256) 722-9985
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