ARM (Thumb Mode) _CPU_Context_switch_arm

[Sebastian Huber]

On 02/25/2013 08:37 PM, Matthew J Fletcher wrote:
> Hi,
>
> I guess it my fault for not 100% copying the rtl22xx BSP into my new one, i had
> the cpsr register in a different state at boot_card() time than the generic ARM
> context switch code expects. I think that common binary blob commercial RTOS
> must do a cpsr read before the first context switch, rather than rely on a
> fixed state as i've not encountered this type of issue before.
>

It is the responsibility of the low-level startup code to set up the C runtime 
environment.  For ARMv4 this is done in

http://git.rtems.org/rtems/tree/c/src/lib/libbsp/arm/shared/start/start.S

Some ARM BSPs still use their own startup file since I don't have the time to 
convert them all.

For ARMv7-M the execution context is set up in a ARMv7-M specific start/stop 
multitasking functions:

http://git.rtems.org/rtems/tree/cpukit/score/src/threadstartmultitasking.c

http://git.rtems.org/rtems/tree/cpukit/score/cpu/arm/armv7m-multitasking-start-stop.c

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Sebastian Huber, embedded brains GmbH

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