KVM vs. Xen?
By user13366129 on Apr 17, 2009
responding to an article on virtualization.info:
KVM is a type-2 hypervisor, Xen is a type-1 hypervisor. So, there is NO apples-to-apples comparison here, you're comparing apples-to-peaches.
Where's the difference?
With KVM ALL your "guests" run in the SAME user-space (there is only one kernel, namely Linux!), and therefore attacking one "guest" from a different "guest" seems way easier then with Xen, where they do get completely separate environments. You would need to HACK into the Xen microkernel to have access, whereas with KVM you have all access directly from your Linux-login.
Is that, what you want? One single unpriviliged user (or any other user!) being able to influence your "guest"? I bet, you don't like that!
If you want to compare KVM with VMware Workstation, Fusion, Parallels, VirtualBox, ok, that would be the right comparison. But nobody does do this comparison. Why?
Because Linux after all still doesn't seem to be "ready for the DataCenter"... OK; I'm making it easy (oversimplifying), but that thinking, expressed in KVM vs. Xen totally ignores many important points that are relevant in datacenters. These do not apply to Laptops, and that's still seemingly the domain of Linux...
Please, start thinking... (I do not want to discredit Linux, but the comparing of apples-and-peaches in this case really is sadening...)