[PATCH] score/i386: Add context switch restore external symbol as a marker.

[Chris Johns]

On 22/07/2016 15:39, Sebastian Huber wrote:
> On 22/07/16 07:30, Chris Johns wrote:
>> On 22/07/2016 15:26, Sebastian Huber wrote:
>>> Could we please use the _CPU_* prefix only for stuff defined by the CPU
>>> port interface and use something like _I386_* for things that are
>>> specific to a particular architecture.
>>
>> I would like this to be added to the formal _CPU_* port interface.
>> Without the marker the CPU will not able to support proper debugging.
>>
>> I see the patch as correct.
>
> To me this looks quite x86 specific.

This is the current target I am working on and the only one I have 
looked at.

> How would you set and use this
> marker on ARM, PowerPC and SPARC for example?

I have not looked at the ARM in detail and would have to look up the 
instructions but a guess would be 'L_restore:' in arm/cpu_asm.S. I do 
not use the PowerPC or SPARC.

The requirement is the marker is the address to set the PC (IP) along 
with the registers held in the TCB so a valid stack frame exists that a 
DWARF unwind'er can unwind. It must exist somewhere in each system or 
the context could not be restored.

Chris