[Xenomai-core] PPC context switch

[somshekar kadam <som_kadam@domain.hid>]

Hi, 

I was understanding the context switch code of
Xenomai-2.3.0 for PPC, I got the point that once it
enters rthal_thread_switch , xnarch_thread_trampoline
function is executed, register 15 holds this address
of this function and register 2 holds the
rthal_thread_trampoline function, 
what I am not able to understand is how does
rthal_thread_switch function is called, 

I understand from rthal_thread_trampoline
xnarch_thread_trampoline is called by jumping to
function using mtlr and in link register has the
address of xnarch_thread_trampoline stored in reg 15
and uses blr to jump to it and executes new thread. 

what I dont understand is how it excutes
rthal_thread_trampoline, may be some pointers on this,
as I am designing the MIPS context switch code for
threads port for xenomai. 

Thanks In advance 
Neelu



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