Re: Running KVM on a Laptop

[TJ <linux@tjworld.net>]

On Wed, 2009-02-18 at 08:45 +0100, Louis-David Mitterrand wrote:
> > Is it not as simple as checking for the svm or vt flags?
> 
> No, one must also check that the bios allows enabling virtualization
> support. My sony laptop has the right processor but no bios option.
> Check that first!

Louis-David, I just noticed your comment in passing and thought I'd let
you (and others with a Sony Vaio) know that it is possible to enable the
VT option in NVRAM even though the BIOS set-up menu doesn't support it.

I did it with this Vaio VGN-FE41Z with T7200 CPU back in mid 2007 and
not had to redo it since. I sometimes run several instances of KVM on
it.

The Phoenix BIOS does support storing in NVRAM and setting the VT-enable
bits using MSR 0x3A at boot time.

I was hoping to create a Linux tool to make the NVRAM change but due to:

 * each BIOS version uses a different token number to store the
VT-enable BIOS setting
 * to identify the token number you have to examine the BIOS executable
code
* currently the only 'safe' way to set the token in NVRAM is to use the
DOS symcmos.exe utility (from Phoenix)

A one-shot solution proved impractical so it is a case of doing it on a
per-BIOS-version basis.

If you want to email me off-list with the precise Sony model-number and
BIOS revision I should be able to help you enable the VT bit.

For some highly technical background see:

http://tjworld.net/wiki/Sony/Vaio/FE41Z/HackingBiosNvram