Re: [PATCH 06/13] scripts/qmp_helper: add support for a timeout logic

[Mauro Carvalho Chehab <mchehab+huawei@kernel.org>]

On Fri, 23 Jan 2026 16:16:03 +0000
Jonathan Cameron via qemu development <qemu-devel@nongnu.org> wrote:

> > >     
> > > > +        for i in range(0, attempts):
> > > > +            try:
> > > > +                obj = self.qmp_monitor.cmd_obj(msg)
> > > > +
> > > > +                if obj and "return" in obj and not obj["return"]:
> > > > +                    break
> > > > +
> > > > +            except Exception as e:                     # pylint: disable=W0718
> > > > +                print(f"Command: {command}")
> > > > +                print(f"Failed to inject error: {e}.")
> > > > +                obj = None
> > > > +
> > > > +            if attempts > 1:
> > > > +                print(f"Error inject attempt {i + 1}/{attempts} failed.")
> > > > +
> > > > +            if i + 1 < attempts:
> > > > +                sleep(0.1)    
> > 
> > ... and here, we sleep for 0.1 seconds.
> >   
> > > 
> > > Do we care about a sleep at the end?  Feels like a micro optimization that
> > > isn't needed.    
> > 
> > This is not a micro-optimization. It is more to ensure that we won't
> > respin it too fast.
> > 
> > What happens is that QMP interface asks the BIOS to send an async
> > message to OSPM, cleaning an ack register. When the OSPM reads the
> > error, it writes 1 to the ack register.
> > 
> > If we send messages too fast, the logic at ghes.c will detect that
> > the ack didn't happen, imediately returning an errocr code.
> > 
> > On such case, we sleep for 100ms before trying again.  
> I was suggesting the opposite.  Just sleep one more time at the end
> before timing out.
> So instead of
> 	if i + 1 < attempts
> 		sleep(0.1)
> 
> simply
> 	sleep(0.1)

If one writes an external loop calling fuzzy with different parameters,
like:

	for i in $(seq 1 360000); do
            scripts/ghes_inject.py fuzzy -T proc-arm;
            scripts/ghes_inject.py fuzzy -T firmware-error;
        done

The extra unneeded would sleep waste 10 hours doing nothing.

Regards,
Mauro