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

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Message-Id: <1222320201.23524.135.camel@alok-dev1>
Date:	Wed, 24 Sep 2008 22:23:21 -0700
From:	Alok Kataria <akataria@...are.com>
To:	"H. Peter Anvin" <hpa@...or.com>
Cc:	Alok kataria <alokkataria1@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Yan Li <elliot.li.tech@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"joerg.roedel@....com" <joerg.roedel@....com>,
	"rjmaomao@...il.com" <rjmaomao@...il.com>,
	Yinghai Lu <yhlu.kernel@...il.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Daniel Hecht <dhecht@...are.com>, Zach Amsden <zach@...are.com>
Subject: Re: [PATCH 1/2] VMware detection support for x86 and x86-64

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

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