> I have plenty of older hardware that cannot support kvm on which
> I would run Xen if it were in the mainline..
KVM is basically QEMU with a kernel module to speed it up. KQEMU is a kernel module to speed up QEMU that doesn't depend on hardware virtualization. So is Xen on old hardware enough faster than QEMU+KQEMU to justify keeping around yet another virtualization platform? That is the billion dollar question Xen is hoping they can answer yes to. Because if they can't Citrix is going to feel really dumb after throwing big sacks 'o cash to own Xen.