Your understanding is correct. KVM provides an acceleration path for QEMU. KVM used QEMU as a base because the hard part of virtualization is to emulate hardware devices, and QEMU already did this well when KVM started. Unfortunately, I don't know of a good writeup on how to disable acceleration since most people want the acceleration. I am sure you can google as well as I can, so I will assume that one doesn't exist... :-) You could unload the kvm modules, blacklilst the kvm module and then get no acceleration. -Bart On Thu, Jun 14, 2012 at 12:32 PM, Robert P. J. Day <rpjday [ at ] crashcourse [ dot ] ca>wrote: > > 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 > > -- > > ======================================================================== > Robert P. J. Day Ottawa, Ontario, CANADA > http://crashcourse.ca > > Twitter: http://twitter.com/rpjday > LinkedIn: http://ca.linkedin.com/in/rpjday > ======================================================================== > > _______________________________________________ > Linux mailing list > Linux [ at ] lists [ dot ] oclug [ dot ] on [ dot ] ca > http://oclug.on.ca/mailman/listinfo/linux >