Re: [Qemu-devel] [PATCH v2 1/6] Use IO port for qemu<->guest BIOS communication.

[Jamie Lokier <jamie@shareable.org>]

Gleb Natapov wrote:
> >> +#define BIOS_CFG_IOPORT 0x1234
> >>   
> >
> > I don't think this is a very safe IO port to use.  Avi suggested that we  
> > advertise the IO port that we use as reserved in the ACPI tables.
> >
> The port number here is just place holder. Any idea of what port we
> should use are welcome. ACPI changes should go into bochs tree and not
> included in this series.
>  
> > I would have chosen something in the low 400/500 range since Bochs is  
> > already using this range for debugging.
> >
> What about 410?

Whatever port is chosen, it should be one which common and rare
operating systems, recent and ancient, don't "probe" to look for
non-PNP ISA devices - unless the protocol requires a magic sequence to
be woken (and goes back to sleep following a CPU reset).

I quick Google suggests 0x410 is most commonly used by PCMCIA ethernet
cards.  I've no idea if they are probed using that port.

-- Jamie