Re: [Qemu-devel] [RFC] icount: warp in the main_loop.

[Paolo Bonzini]

Il 04/07/2014 09:30, Frederic Konrad ha scritto:
> >   +    /*
> > +     * In icount mode, sometimes the VCPU is blocked and an event is
> > needed to
> > +     * continue.
> > +     * Just warp to make the time grows and have a chance to run the
> > CPU.
> > +     */
> > +    qemu_clock_warp(QEMU_CLOCK_VIRTUAL);
> >       return ret;
> >   }
> Paolo,
> You mentioned some icount patches (I can't find where) can you point me
> to them?
> Did you already had this bug?

Why is this needed?  It's possible that a qemu_clock_warp code is 
missing somewhere, but for timers it should be handled here:

static void timerlist_rearm(QEMUTimerList *timer_list)
{
    /* Interrupt execution to force deadline recalculation.  */
    qemu_clock_warp(timer_list->clock->type);
    timerlist_notify(timer_list);
}

If the VCPU is blocked, it will set vm_clock_warp_start to the realtime 
clock value ("clock") a QEMU_CLOCK_REALTIME timer to the next deadline 
("clock + deadline").  At the next deadline, icount_warp_rt will 
increase QEMU_CLOCK_VIRTUAL by "clock - vm_clock_warp_state" which 
should trigger the clock event.

Paolo