[linux-elitists] Virtualization

Greg KH greg@kroah.com
Tue Feb 22 20:51:26 PST 2005

On Wed, Feb 23, 2005 at 12:58:05AM +0000, Adam Sampson wrote:
> The research group I'm in is currently looking at Xen because it
> should make a pretty nice environment for developing an OS: it
> provides standard virtual devices, so we can just write one set of
> network/video/disk drivers and still get reasonable performance, and
> we can run it at effectively native speed alongside Linux on our
> cluster nodes.

Heh, research people _hate_ to write drivers.  Getting their hands dirty
with all that "real world" stuff like flaky hardware :)

And you're not alone.  K42 uses Linux's drivers.  So does HURD.  The
problem is, everyone forgets that drivers really matter in the end.  The
Xen people are just starting to realize this, as people want to have
access to their hardware from within their virtual machines (like
getting to that USB flash stick that was just plugged in, or your 5
button USB mouse / FM tuner.) and they don't like slow access either.

I know some of the people that are finally starting to look into this
problem, and hopefully they can come up with a standardized virtual
driver.  Instead of the 9 different virtual disk drivers that I think
already have in the kernel tree.

And if we do that, I see no reason why vmware can't use those drivers
too, so they can finally drop their weird add-on kernel module that is a
giant pain-in-the-butt for their users.

> They've got some cool-looking image migration stuff too (a colleague
> described moving a Linux system playing video between PCs without
> noticable interruption). Yes, it's definitely cheating, but it's
> pretty non-intrusive cheating, and the result is actually useful...

Also, a certain next-gen gaming system uses virtual machines running on
Linux to handle access to the hardware in a sane manner, and do things
like running network accessable processes in one virtual machine,
protecting the rest of the box from potential problems.

But I'm with Don on this one, there is just too much hype about "virtual
machines" floating around these days that isn't justified by real
solutions to real problems.

greg k-h

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