F16: Sandy Bridge -> lags, missing effects, ui-crashes

[Adam Williamson]

On Thu, 2012-05-31 at 20:47 +0100, Richard W.M. Jones wrote:
> On Thu, May 31, 2012 at 02:42:11PM -0500, Chris Adams wrote:
> > Once upon a time, Adam Williamson <awilliam at redhat.com> said:
> > > On Tue, 2012-05-29 at 20:36 -0400, Jared K. Smith wrote:
> > > > Yes, that's a possible culprit. I've had massive problems with VT-d
> > > > enabled on both a Thinkpad T510 and on a Thinkpad X220.  I don't
> > > > pretend to understand what advantages VT-d is *supposed* to give me,
> > > > but it's the first thing I turn off in the BIOS.  In fact, on the
> > > > T510, I couldn't even get an installation to complete without turning
> > > > it off.
> > > 
> > > You need it to run as a KVM host with anything resembling speed.
> > 
> > Isn't VT-d only for VMs directly talking to the hardware, bypassing the
> > host?  You can run VMs with decent speed using virtualized drivers
> > without VT-d (and unless you have storage controllers and network
> > interfaces dedicated to each VM, virtualized drivers is the only secure
> > method).
> 
> That's right.  VT-d allows the I/O port space to be partitioned like
> memory, so that devices (SCSI disks etc) can be passed directly to
> guests which can use them without (in theory) compromising the host,
> eg. issuing DMA requests to overwrite host kernel memory.
> 
> VT-x is what Intel calls the regular hardware virtualization
> extensions.

Gah. Sorry, I stopped reading after VT-. =)
-- 
Adam Williamson
Fedora QA Community Monkey
IRC: adamw | Twitter: AdamW_Fedora | identi.ca: adamwfedora
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