Paolo Bonzini <pbonz...@redhat.com> writes:
> On 17/12/19 14:42, Alex Bennée wrote: >>> Why do you need to set exception_index to something other than -1 (using >>> cpu_loop_exit_noexc for example)? >> If there is no exception to process we won't exit the main loop which we >> need to do if we want to wait until there is data to read. > > Okay. > >>> Using ->stop here is a bit weird, since ->stop is usually related to >>> pause_all_vcpus. >> >> Arguably we could come up with a better API to cpu.c but this allows us >> to use cpu_resume(c->sleeping_cpu) when waking up rather than hand >> rolling our own wake-up mechanism. > > But we already have the right wake-up mechanism, which is > cpu->halted/cpu_has_work. cpu_has_work is a guest function though and semihosting_console is a common hw module. It can't peek into the guests internal state. This all comes back to cpu_thread_is_idle anyway in making our decision about if we do or do not sleep on the halt_cond. > That also makes it possible to just use > EXCP_HALTED instead of adding a new EXCP_BLOCKED. We can certainly use EXCP_HALTED but maybe come up with a common way of entering the state? There seems to be a combination of messing around with special interrupts and direct poking of cs->halted = 1 while setting the exception. Maybe this could finally clear up the #if defined(TARGET_I386) hacking in cpus.c? > > Paolo -- Alex Bennée
