Re: [Xen-users] No Full Virtualisation with Intel Core 2 Duo T5500 Mobile CPU?

[Falko Tesch <falko.tesch@xxxxxxxxxxx>]

Hi Folks,

thanks to all of you for our answers.
I just filed a feature request to MSI to implement such BIOS setting, 
I'll keep you updated on any news...
Regards
Falko

Petersson, Mats schrieb:
>  
>
> > -----Original Message-----
> > From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> > [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of 
> > Karl Stevens
> > Sent: 12 February 2007 19:18
> > To: Falko Tesch
> > Cc: xen-users@xxxxxxxxxxxxxxxxxxx
> > Subject: Re: [Xen-users] No Full Virtualisation with Intel 
> > Core 2 Duo T5500 Mobile CPU?
> > -----BEGIN PGP SIGNED MESSAGE-----
> > Hash: SHA1
> >
> > Falko Tesch wrote:
> > > Hello,
> > >
> > > I have some interesting issue with Intel VT CPU and XEN 3.0.2:
> > >
> > > I'm running XEN 3.0.2 on a MSI Fuzzy 945GM2 Mainboard
> > (http://www.msi.com.tw/program/products/ic/ic_detail.php?prod_
> > no=4) with
> > > a Intel Core 2 Duo Mobile CPU (T5500).
> > >
> > > When booting the mainboard BIOS says it found a EM64T CPU, which is
> > > AFAIK the code for a Intel CPU with Virtualisation Technologie.
> > > But whether Linux nor XEN detects this CPU as a VT CPU.
> Just to clarify, EM64T is Intel's name for x86-64 (aka AMD64), so it's
> the 64-bit extensions to the x86 architecture. This is NOT directly
> related to Intel's VT. 
>
> > > Who's right, the mainboard or Linux?
> > Probably both.  Intel allows the BIOS to disable the VT 
> > instructions at
> > boot time.
> Since you're looking at different features, we can't say one is right or
> wrong. Obviously, the core-duo processor shouls support VT and 64-bit
> architecture.
> > If the BIOS allows you to enable it (most manufacturers leave it
> > disabled by default) you will need to power-cycle the machine after
> > doing so (just rebooting won't work - the machine needs to be off for
> > the option to be enabled properly.)
> This is correct, you will need to enable the feature in BIOS (or
> technically speaking "Not set the disable bit"!) in the BIOS during
> startup. Since this is a "can't clear" bit, once it's been written, it
> can't be reset in software, you'll have to power-cycle as Karl says. 
>
> It's worth noting also that there are BIOS's that don't allow this bit
> to be turned on/off - they just lock it without giving the user any
> options to change the setting. 
>
> --
> Mats
> > - -Karl
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