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Re: [Qemu-devel] About qemu emulation speed (a question) and supported O
From: |
Mark Williamson |
Subject: |
Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS |
Date: |
Wed, 14 Sep 2005 04:48:24 +0100 |
User-agent: |
KMail/1.8 |
> >No, I got the impression that Fabrice was taking about virtualization the
> > way VMware, old plex86, and vmbear (new FOSS x86 virtualizer in the
> > works) do it.
>
> The x86 cannot be "virtualized" in the Popek/Goldberg sense, so there's
> a couple of fast emulation techniques that are possible. Other than a
> hand coded dynamic translator, I reckon qemu + kqemu is about as good as
> it can get (unless I'm missing something here). Do you have
Well, VMware does manage direct execution of some kernel code, I believe.
VMware's real super-cunningness is doing this as much as they can, instead of
emulating all the stuff. That said, I think with suitable optimisations
emulating all the kernel code could be acceptable.
The unfortunate thing is that the guest can still tell it's in a VMware
machine (I'm not clear how) so it's not really *full* virtualisation, it's
just about epsilon away from it :-) VT / SVM will solve this properly.
> There are a couple of interesting paravirtualization techniques too.
> There's the Xen approach (really fast, but very invasive), the L4ka
> afterburning (theoritically close to as fast, but less invasive), and
> then of course the extremes like UML.
The original L4 port of Linux was pretty hard-core stuff. I understand later
L4 developments made native ports easier. The afterburner stuff seems to be
the next generation of coolness!
The afterburning is really neat stuff :-) You can use one kernel for native,
L4 guest and Xen guest. The kernel actually does some of the virtualisation
work itself by doing (tasteful levels of) self-rewriting / device emulation
on its own. You can run normal device drivers, etc. This has to be assisted
by some compiler tool-chain stuff that allows the runtime "wedge" to do its
job.
They have a (crazy but cool) idea that they'll one day be able to live-migrate
(i.e. without more than a few hundred ms downtime) virtual machines between
L4 hypervisors and Xen hypervisors.
Cheers,
Mark
> >>FWIW, Xen is already using QEMU in this way. It would be very neat to
> >>see this technique applied to a Type II VMM.
> >
> >Do you have any details on this?
>
> Mark did a really good job of summarizing the current architecture.
>
> Regards,
>
> Anthony Liguori
>
> >>Regards,
> >>
> >>Anthony Liguori
> >>
> >>
> >>_______________________________________________
> >>Qemu-devel mailing list
> >>address@hidden
> >>http://lists.nongnu.org/mailman/listinfo/qemu-devel
>
> _______________________________________________
> Qemu-devel mailing list
> address@hidden
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
- [Qemu-devel] About qemu emulation speed (a question) and supported OS, Alexandre Leclerc, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Adrian Smarzewski, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Jim C. Brown, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Anthony Liguori, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Jim C. Brown, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Mark Williamson, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Anthony Liguori, 2005/09/13
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS,
Mark Williamson <=
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Anthony Liguori, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Mike Swanson, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Jim C. Brown, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Anthony Liguori, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Jim C. Brown, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Jim C. Brown, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Henrik Nordstrom, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Mark Williamson, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, John R. Hogerhuis, 2005/09/14
- Re: [Qemu-devel] About qemu emulation speed (a question) and supported OS, Jim C. Brown, 2005/09/14