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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [6391] Fix nographic mode and VNC
Date: Thu, 22 Jan 2009 00:04:10 +0000
References: <E1LPikI-0005cS-RK@cvs.savannah.gnu.org>
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To: qemu-devel@nongnu.org
Cc: Blue Swirl <blauwirbel@gmail.com>

> >  > > > +static void nographic_update(void *opaque)
> >  > > >
> >  > >  > +{
> >  > >  > +    uint64_t interval = GUI_REFRESH_INTERVAL;
> >  > >  > +
> >  > >  > +    qemu_mod_timer(nographic_timer, interval +
> >  > >  > qemu_get_clock(rt_clock)); +}
> >  > >
> >  > > Maybe less often than 33 times per second?  SDL uses 2 times per
> >  > > second when the window is minimized.
> >  >
> >  > I just tried: it's not enough, the serial console is unusably slow.
> >
> > Mmm, I haven't followed everything so I probably misunderstand, but I
> >  guess you are talking about a serial console on stdio, shouldn't we
> >  already be monitoring the stdin fd to break the cpu emulation loop?
>
> Some other way, like SIGIO or IO worker thread, may work too. It may
> also be a big change.

Using a side effect of the the gui refresh timer to implement IO polling is 
absolutely the wrong way to fix things.

All IO should be event driven. If it isn't then then it needs fixing. The 
polling timeout is determined by timeout = 5000 in vl.c.

Paul