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[OCLUG-Tech] running QEMU without KVM, a newbie question

  i've dabbled with QEMU and KVM but never sat down and taken a hard
look at them, and now i'm a bit confused about how they fit together,
so i'm going to ask a really simple question or two which might clear
everything up.

  based on what i've read over the last few hours, it appears that
QEMU is quite happy virtualizing stuff with no actual need for KVM.
instead, KVM simply allows QEMU to take advantage of H/W
virtualization (intel's VT, amd's AMD-V) for *much* improved
performance by giving QEMU access to the additional
virtualization-related paging features of the hardware.  is that about
right?

  that *sounds* like what's happening as you can read here:

http://wiki.qemu.org/KVM

"KVM (Kernel Virtual Machine) is a Linux kernel module that allows a
user space program to utilize the hardware virtualization features of
various processors. Today, it supports recent Intel and AMD processors
(x86 and x86_64), PPC 440, PPC 970, and S/390 processors.

"QEMU can make use of KVM when running a target architecture that is
the same as the host architecture. For instance, when running
qemu-system-x86 on an x86 compatible processor, you can take advantage
of the KVM acceleration - giving you benefit for your host and your
guest system."

  note the use of phrases like "can make use of" and "take advantage
of", suggesting that KVM is great to have, but not *required* for
running QEMU.

  in addition, check out some of the command-line options for "qemu"

$ qemu-system-x86_64 -h
... snip ...
-enable-kvm
...
-no-kvm
-no-kvm-irqchip
-no-kvm-pit
...

  and so on, clearly suggesting that you can start any of the
appropriate QEMU commands while *explicitly* disabling some or all of
KVM support.

  is my understanding correct?  is there a decent writeup of this
online somewhere, clarifying this distinction?  thanks.

rday

-- 

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Robert P. J. Day                                 Ottawa, Ontario, CANADA
                        http://crashcourse.ca

Twitter:                                       http://twitter.com/rpjday
LinkedIn:                               http://ca.linkedin.com/in/rpjday
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