How important is TXT and VT-d?

[Lennart Sorensen]

On Wed, Mar 28, 2012 at 09:48:43AM -0400, Giles Orr wrote:
> My desktop is getting a little long in the tooth and I'm thinking
> about eventually replacing it with a laptop.  I'd like the laptop to
> be an i7 quad core - which probably means either poor battery life or
> a very heavy battery, but that's okay as it would mostly be a desktop
> replacement rather than something to carry around.  Right at the
> moment the majority of readily available laptops that have a quad core
> Intel have the Core i7 2670QM processor, which according to Wikipedia
> ( https://en.wikipedia.org/wiki/List_of_Intel_Core_i7_microprocessors
> ) doesn't support TXT or Intel VT-d.  Given that the first thing I'd
> do is install Linux on the thing, the loss of TXT doesn't sound too
> onerous (correct me if I'm wrong, that's why I'm sending this email).
> The other part, VT-d ... as I read it, that means I'd have VT-x, but
> virtual machines wouldn't have direct access to hardware.  Am I
> reading this correctly?  And, given that I've never used processor
> level virtualization before and, honestly, I might never (but would
> like to have the option), should I really care about this?

VT-d is really only useful if you want to give a physical piece of
hardware to a virtual machine.  So if you wanted to dedicate a PCI
network card to a virtual machine and not have the host machine use it,
VT-d allows that to be done.

I have no idea why anyone would need TXT for anything other than DRM.

> There are a couple other quad core i7s commonly available on the
> consumer market, but they're also lacking TXT and VT-d so this
> question doesn't seem likely to go away.

I consider the CPU virtualization extensions essential.  The device
virtualization extensions (vt-d) are merely interesting, but far from
essential.  Now if you needed to dedicate a piece of hardware to a VM
you would probably consider it essential.

Of course you can already assign a USB device to a virtual machine as
far as I remember without any need for VT-d which I consider to cover
the cases I would care about.

-- 
Len Sorensen
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