Optimization issue in RISC-V BSP

[Denis Obrezkov]

>
> > + Special registers
> Yes, this might be the issue, specifically if the port is using
> interrupts. For example, mstatus/mcause/mepc might need to be saved
> and/or reset.
>
> What I'm suspicious of is that the trap_entry code is the problem,
> since it didn't have a chance to get executed/tested on my Spike
> (dummy clock simulated) BSP/Spike, especially after updating the port
> from 2015 to 2017 (RISC-V ABI has changed).
>
> >
> > If it is not preserved across a subroutine call, then it does not have
> to be
> > in the context switch but is in the ISR context.
> >
> > If it is preserved across subroutine calls, then it is in the context
> > switch.
> >
> > Special registers have to be analyzed. Some may have a magic value across
> > the entire system life. Others will require special handling.
> >
> > Every register needs to be logically places in a class for management
> > purposes.
> >
> >
> >> As for now, I am getting an error on mret instruction, I will try to
> >> figure
> >> out tomorrow, why it happens.
> >> Also, in my debugger 'display /i $pc' suddenly started to work properly.
> >> So, now I can debug a bit more efficient.
> >> --
> >> Regards, Denis Obrezkov
> >
> >
> >
> > --
> > Hesham
> >
> >
>
>
>
> --
> Hesham
>
Hello, interrupt-driven clock driver works to some extent!

*** LOW MEMORY CLOCK TICK TEST ***

TA1 - rtems_clock_get_tod - 09:00:00 12/31/1988

TA2 - rtems_clock_get_tod - 09:00:00 12/31/1988

TA3 - rtems_clock_get_tod - 09:00:00 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:04 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:09 12/31/1988

TA2 - rtems_clock_get_tod - 09:00:10 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:14 12/31/1988

TA3 - rtems_clock_get_tod - 09:00:15 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:19 12/31/1988

TA2 - rtems_clock_get_tod - 09:00:20 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:24 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:29 12/31/1988

TA3 - rtems_clock_get_tod - 09:00:30 12/31/1988

TA2 - rtems_clock_get_tod - 09:00:30 12/31/1988

TA1 - rtems_clock_get_tod - 09:00:34 12/31/1988

*** END OF LOW MEMORY CLOCK TICK TEST ***

Fatal Error 5.0 Halted

I've started to save and restore mepc and mcause registers, though, they
are handled differently in the
provided example.

Also, the optimized version doesn't work.
-- 
Regards, Denis Obrezkov
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