RTEMS SMP implementation questions

[Hesham Moustafa]

Hi all,

I have been implementing SMP for a new architecture (Epiphany) and I
have some questions.

When the secondary processor should be waiting (or going to idle
state)? At Thread_Start_multitasking?

When a secondary processor is interrupted by another one? When it's
allocated a thread (lazy allocate)? And in that case, what's the
interprocess interrupt handler should do?

The current SMP interrupt handler checks for the type of the message
(shutdown, test, cache, etc). Should the interrupt handler assembly
code check for dispatch necessary (which is set by another processor
that allocated a thread for it), and then executes this thread? Please
correct me if I am wrong. And if this is correct, where the secondary
processor should be waiting (which function)?

One major question, what's exactly the must-be-added code to both
Context Switch, and ISR Handler, that differs from uni-processor
systems.

When I tried to run smp01 with my current implementation, I noticed
that the boot processor goes to IDLE thread after initialization, and
a secondary processor is the one who executes Init, is that the
correct behaviour? I think it's not, although the boot processor does
all its necessary functions before restart itself and jump to idle
task, and it's allocating Init to processor 1.

[1] https://github.com/heshamelmatary/rtems-epiphany

Regards,
Hesham