CSR_VSTIMECMP
ncsr_write(CSR_VSTIMECMP, ULONG_MAX);
ncsr_write(CSR_VSTIMECMP, (u32)(t->next_cycles));
ncsr_write(CSR_VSTIMECMP, t->next_cycles);
t->next_cycles = ncsr_read(CSR_VSTIMECMP);
t->next_cycles = ncsr_read(CSR_VSTIMECMP);
csr_write(CSR_VSTIMECMP, -1UL);
ncsr_write(CSR_VSTIMECMP, ULONG_MAX);
ncsr_write(CSR_VSTIMECMP, (u32)ncycles);
ncsr_write(CSR_VSTIMECMP, ncycles);