Re: [PATCH 1/2] VMware detection support for x86 and x86-64

Alok Kataria
2008-09-25T05:23:30Z

On Wed, 2008-09-24 at 22:04 -0700, H. Peter Anvin wrote:
> Alok Kataria wrote:
> >>>
> >> You accessed a bloody I/O port!
> >>
> >> If you think it's harmless because it was an IN, you're sorely mistaken.
> >
> > Hi Peter,
> >
> > It would be really helpful if you could explain me when can this go
> > wrong or what kinds of problems can this cause on native hardware.
> >
>
> You accessed an unknown I/O port.
>
> This means you caused an unknown action in an unknown peripheral device.
>
> This could cause ANYTHING to happen.

Hmm...what can a IN on an unknown port cause on native hardware, if a
port is not being used it would return 0xFFFFFFFF in eax, and if you
have a real device there (a sane one), what can IN result in apart from
reading some IO register/counter value in eax ?
If there is anything apart from the above 2 outcomes, please let me know
exactly what you mean.

Thanks,
Alok