Re: [Qemu-devel] International Virtualization Conference

[Rob Landley <rob@landley.net>]

On Tuesday 10 October 2006 1:18 pm, Jim C. Brown wrote:
> On Tue, Oct 10, 2006 at 11:48:33AM -0400, Rob Landley wrote:
> > > Here you are using the terms "virtual" and "emulated" interchangably. 
That's
> > > ok as long as the difference between virtualization and virtual/emulated 
is
> > > understood. 
> > 
> > Well, the hardware people see a huge difference.  To them one is "doing it 
in 
> > hardware" and the other is "doing it in software".
> > 
> 
> That is not how he uses the terms. He uses them interchangably.

A) I'm not a hardware person.

B) The people I've seen care about this are embedded system developers, who 
also make a distinction between "emulator" and "simulator".  (One is a 
hardware board that fakes a certain processor, the other is software that 
does the same thing.  Sometimes, I can even keep them straight.)

> I was just trying to make clear the difference between emulation and
> virtualization. 

I consider this difference an implementation detail that's likely to vanish 
into obscurity as time goes on.

> > 
> > > If I follow your logic, then bochs is also a good canidate for the 
workshop.
> > 
> > If you mean the way Hurd is a candidate for a workshop anywhere Linux is, 
> > sure.
> 
> I was trying to say that qemu (sans kqemu) is a bad candidate. Someone else
> explains the virtualization-vs-emulation thing much better than I could
> (short answer: VMware, kqemu, and other virtualizers do it in the hardware
> whie emulators like qemu and bochs do fully it in the software).   

Modems wandered back and forth between hardware and software before dying.  
Hardware crypto accelerators were really popular a few years back.  One of 
the promises of the cell chip is doing stuff like 3D rending and mp4 
compression entirely in software at a reasonable speed.  And now it's 
only "virtual reality" if you use an actual 3D graphics chip, with software 
rendering it's just "emulated reality".  Right.

The "this must be done in hardware to get reasonable performance" people are 
always amusing, in retrospect.  Personally, I've never bothered to even 
install kqemu.  Maybe when Moore's law stops because we've finally hit atomic 
limits or whatever, I'll start to care.

Rob
-- 
"Perfection is reached, not when there is no longer anything to add, but when 
there is no longer anything to take away." - Antoine de Saint-Exupery