On Mon, May 05, 2008 at 08:58:04AM +0300, Shachar Shemesh wrote: > Muli Ben-Yehuda wrote: >> >>> KVM, Xen and VMWare ESX are just different implementations of the >>> same technology, >>> >> >> Sure, just like Windows and Linux are just different >> implementations of the same technology. >> > I'll clarify. > > KVM, Xen and VMWare ESX reside in one category for > virtualization. The other VMWares, VirtualBox, Virtual PC for > Windows, DosBox and Qemu with the acceleration reside in > another. Qemu in its pure form (as well as when running non Intel > platforms), Virtual PC for Mac on Power PC, as well as the Commodor > 64 and Apple II emulators, UAE, and a host of other emulators reside > in a third category. > > The first enslave the entire host OS for the purpose of running the > virtualization (hypervisors),
This might be correct for ESX, but is wrong for Xen and definitely wrong for KVM. A Linux machine which has KVM loaded can do everything it did before KVM was loaded, as well as run other virtual machines. How did KVM "enslave" the host OS? > the second are basically user space programs (with some "cheating") > which use the CPU capabilities for some virtualization enhancements, This applies equally well to the qemu+KVM combination, and if you look at it from the right angle, even applies to Xen+qemu-dm. The differences between emulation and virtualization are pretty blurry. Once you get beyond the superficialities, you can talk about a spectrum, but not about clear cut lines. > and the third are complete emulation, from the grounds up, emulating > every aspect of the destination machines. Puristically speaking, > only the third category can really be called "emulators". In that > respect, KVM, Xen and VMWare ESX just different implementations of > the same technology. Linux and Windows are both operating systems (originally) for x86 hardware, unlike hypervisors or userspace applications. In that respect, Linux and Windows are just different implementations of the same technology... Cheers, Muli ================================================================= To unsubscribe, send mail to [EMAIL PROTECTED] with the word "unsubscribe" in the message body, e.g., run the command echo unsubscribe | mail [EMAIL PROTECTED]
