pussuw commented on PR #5985:
URL: https://github.com/apache/incubator-nuttx/pull/5985#issuecomment-1089252057
> setintstack is implemented by chip, so you can define setintstack in mpfs
to fetch the interrupt stack pointer from scratch register without breaking
other chip's implementation. Basically, you can:
>
> 1. Add the interrupt stack pointer to percpu struct
>
> 2. Define setintstack in mpfs to return it
>
>
> Other chip could reuse this, or the developer can provide setintstack in
other way if they have a better solution.
Yes this is workable.
I was worried because now the equivalent of "setintstack" is in the common
code, I think I can provide a solution for the common code too. Something like:
```
#if CONFIG_ARCH_INTERRUPTSTACK > 15
.macro setintstack, tmp0, tmp1
#ifndef CONFIG_ARCH_USE_SMODE
#if SMP_NCPUS > 1
csrr \tmp0, mhartid
li \tmp1, (CONFIG_ARCH_INTERRUPTSTACK & ~15)
mul \tmp1, \tmp0, \tmp1
la \tmp0, g_intstacktop
sub sp, \tmp0, \tmp1
#else
la sp, g_intstacktop
#endif
#else
csrr \tmp0, CSR_SCRATCH
REGLOAD \tmp1, RISCV_PERCPU_IRQSTACK(\tmp0)
mv sp, \tmp1
.endm
#endif /* CONFIG_ARCH_USE_SMODE */
#endif /* CONFIG_ARCH_INTERRUPTSTACK > 15 */
```
Maybe needs a bit of fixing / tidying up but the basic idea would be like
that. You need the percpu structure if the kernel is in S-mode. That cannot be
avoided.
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