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Subject: Re: [PATCH 1/2] VMware detection support for x86 and x86-64
From: Alok Kataria <akataria@vmware.com>
Reply-To: akataria@vmware.com
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Alok kataria <alokkataria1@gmail.com>, Ingo Molnar <mingo@elte.hu>,
       Yan Li <elliot.li.tech@gmail.com>,
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Organization: VMware INC.
Date: Wed, 24 Sep 2008 21:46:18 -0700
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On Wed, 2008-09-24 at 21:38 -0700, H. Peter Anvin wrote:
> Alok kataria wrote:
> >
> > Even if there is anything on that port on native hardware it would
> > work perfectly well and is _safe_.
> > First let me post the code to access this backdoor port (the way it
> > should really be done )
> >
> > So whenever we query port  0x5658 , with the GETVERSION command (which
> > is the first thing we do with this port), we expect that  eax !=
> > 0xFFFFFFFF   and ebx has a  VMWARE specific MAGIC value.  Please note
> > that ebx has been initialized to zero in the code above.
> >
> 
> You have no idea what you just did to a real piece of hardware.
Why ? what do you mean ? 
ebx is a local variable in the code above that i posted. 
Only when on hypervisor will we write the magic value over there.
How can this affect native hardware, i fail to understand. 
Please explain.

Thanks,
Alok
> 
>         -hpa