Optimization issue in RISC-V BSP

[Sebastian Huber]

On 28/07/17 15:15, Denis Obrezkov wrote:

> 2017-07-28 14:56 GMT+02:00 Joel Sherrill <joel at rtems.org 
> <mailto:joel at rtems.org>>:
>
>     There is a debug option near the bottom of confdefs.h which you
>     can enable to generate a data structure filled in with various
>     values computed by confdefs. You can look at that in gdb without
>     loading it on the target.
>
>     It is probably worth it to look at that now and see what you spot.
>
> Okay, I'll try.
>
>
>     And a random thought.. what's the interrupt stack size and how is
>     it allocated? What are the port specific related macros set to?
>
> I don't completely understand what is the interrupt stack. Because, 
> when an interrupt occurs,
> I save all registers and move the stack pointer, handle interrupt,

Now you handle the interrupt on the stack of the interrupted context 
(usually a thread). So, you must take this overhead into account for 
every thread. If you switch to an interrupt stack, then you only have to 
account for one interrupt frame per thread. If you support nested 
interrupts, you need even more space per thread without an interrupt stack.

> restore registers and move stack
> pointer back.
> -- 
> Regards, Denis Obrezkov
>
>
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