There is a tool out there, called symcmos from Phoenix Ltd, e.g. here:
http://www.filewatcher.com/b/ftp/ftp.supermicro.com/utility.0.0.html

I own a SZ1XP (architecture is very similar to other VAIOs based on Intel Core Duo (2)) and used it to enable the VT feature by means of a dos bootdisk and dumping my original cmos settings:

symcmos -v2 -lcmos.sav

editing register 399 from [0000] to [0001] and loaded the modified settings back:

symcmos -v2 -ucmos.sav

Now the catch: this register is possibly only valid for my model and the latest available Bios (R0092N0) for it - so it's still somewhat risky to find the correct register by trial/error. Also there are a lot of them... but it's doable. I only found one show-killer - a single register will pop up a red line and asks something like: "Do you really want to enable Service/Rescue Mode? (y/n)" --> don't get tempted, it's a trick (or an old leftover or something else): if you press 'y', anything which prints more than a few lines out will freeze the system - even the bios menu itself. If something goes terribly wrong (like this show-killer)- you need to either run the tool again with parameter -d (clear cmos) or if you can't do this anymore, disassemble the laptop and disconnect the cmos battery.

By the way, I also tried the other way and used this Phoenix Bios Editor Pro tool (V2.1) - just do a search on the intel.com download center for "phoenix" and get BiosEdit2100.zip - they intented it for logo change, but it's the real deal to even build bios images. I am sure, it would work great, if Sony isn't so much "stay customized with every piece of OEM product you've bought in": A modified bios (where e.g. the VT feature is enabled) is generated without errors or warnings, BUT it will destroy any ACPI related functionality and do other nasty things, if really flashed. This means: WinXP will not boot anymore (BSOD) and Linux will work only when pnpbios and acpi is disabled. Without WinXP you can't flash a good bios back - so you are basically lost: no DOS tools or Phoenix CRISIS recovery disk will save you: Sony made sure of it (bios image and flash procedure is customized and there is no DOS version available).

Needless to say that you void your warranty and will possibly turn your laptop into a brick if you follow any of my instructions - for me it worked out fine and if I've found the info I just posted it would have saved me a lot of time and stress

Cheers,
Bernhard

You could do it that way (change only registers which are set to [0000] and leave all other alone) one by one and spend a lot of hours or you could just set the first half of all zeroed registers to one, check if the VT bit is set, if no: restore your original cmos and try the other half - if yes: only change half of the registers to one within the found set, check again and repeat (binary search principle).

But I would try register 399 (on line 210 of the generated cmos file) first - maybe you're lucky!

Not that I could think of. If I'd design the bios, I would not ultimately trust the settings read from cmos (there could be corruption or a changed layout after a bios update where the checksum is still valid for invalid data) and thus would not trigger any functionality which permanently bricks the boot process.

Good luck and let me know about the outcome, if you try it!

'Restore Defaults' will change all settings back. Like I said, there is only one range (or even only one register) which could cause real troubles - maybe (after I played a little bit more around) unrelated to the register which causes the red lined question during boot up to turn on 'Service/Repair/Debug mode': So I highly recommend to get rid of boot/bios passwords and fingerprint protection (if your notebook has one) - so that you can at least boot into DOS and clear the CMOS without the need to open the laptop and remove the battery (which, by the way, works great too).

Sorry, no performance tests - currently not even a VMware installation and I wouldn't expect any or much gains there: a guest has already run only within a margin of 5-10% slower than on real hardware before VT was there.

While viewing the VAIO BIOS content with Phoenix BIOS Editor, there's a hidden "Debug Intel Menu" which contains the setting to enable VT. Is it possible to use the symcmos utility to make that menu appear? The menu had this information next to it: "This menu is shown', 0Dh, 'by ESID[3:2]=01b." I assume 0Dh is a carriage return and 01b = 01(BINARY). Does anyone know what ESID stands for and what it correlates to?

Bfroemel, how exactly did you discover that the 399th register bit had anything to do with the VT option?

Sounds like good news! Does this mean i have a chance to enable VT on my Sony Vaio VGN-AR21S ? This would be great!

I own a Sony VGN-AR21S with R200J6 bios from a AR31S (needed the bios to upgrade the cpu - T7600)

symcmos -v2 -lcmos.sav

editing register 195 from 0000 to 0001 and loaded the modified settings back:

symcmos -v2 -ucmos.sav

VT now enabled on both CPU's.

Just got my VGN-FE890 working with VT enabled on CPU 0,1

R0200J3 BIOS using 0x0195

Thanks for the advice!

Has anyone tried this on a VAIO VGN-F21M?

Why is the VT setting not on by default anyway?

Thanks

Damon