ARM (Thumb Mode) _CPU_Context_switch_arm

[Matthew J Fletcher]

Sebastian,

The _Thread_Heir->Registers are ok into the _Context_Switch() call, sp and
lr both sensible.

At the 'mrs r2, cpsr' line sp is 0x40001b2c (rubbish) and pc sensible.

In _restore, after the 'ldmia r1, ...' instruction the sp and lr are loaded
with the correct values from _Thread_Heir->Registers.

Its the 'msr cpsr, r2' messes up the sp and lr




On 25 February 2013 08:04, Sebastian Huber <
sebastian.huber at embedded-brains.de> wrote:

> On 02/22/2013 06:31 PM, Matthew J Fletcher wrote:
>
>> Hi,
>>
>>  >Which code is at address 0x7fffe369 - 1?  The context will be
>> initialized in
>> the function >_Thread_Load_environment().
>>
>> I believe that's the issue, there is no code at that address, code starts
>> at
>> 0x81000000
>>
>> In _Thread_Start(), i can see that the_thread->Start.entry_point is set to
>> 0x81007219, which is the Init() function.
>>
>
> This Start structure is irrelevant for the context switch.
>
>
>
>> I can also see _Thread_Load_environment() set the stack and the entry
>> point
>> correctly, the _Thread_Heir->Registers contains the correct information
>> into
>> passed into _Context_Switch.
>>
>> But by the 'bx lr' line in _restore the sp and lr registers are showing
>> the
>> wrong values, well gdb says they are wrong anyway, the sp is now
>> 0x40001c80
>> which is not even ram, and the lr is before code space.
>>
>
> Are the values (sp and lr) of heir context correct on entry of the first
> _CPU_Context_switch()?
>
>
>
>> Doing a single instruction step sets the pc to 0x7fffe368, so it looks
>> like its
>> branched to that address, the next instruction will fault as its just
>> some rubbish.
>>
>> Is it possible this code is wrong for the arm7tdmi ? its not exactly
>> cutting
>> edge now, there are commends in the context switch code that it was
>> tested on a
>> arm7tdmi but with different instructions, was this code diffrent in the
>> past ?
>>
>
> The context switch code is unchanged since 2002 and it works well.  I
> suppose something is wrong with the call to _CPU_Context_switch() or the
> heir context.  I can only help you with the latest RTEMS master branch
> since this is what I am using.
>
>
> --
> Sebastian Huber, embedded brains GmbH
>
> Address : Dornierstr. 4, D-82178 Puchheim, Germany
> Phone   : +49 89 189 47 41-16
> Fax     : +49 89 189 47 41-09
> E-Mail  : sebastian.huber at embedded-**brains.de<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
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rtems.org/pipermail/users/attachments/20130225/1d6e703c/attachment-0001.html>