GNU libc maintainer defends KVM

Ulrich Drepper, lead maintainer of Linux C library since 1996 and employed at Red Hat, worte an interesting post about KVM on his personal blog:

With KVM proving more and more that it is viable Xensource and VMWare start sandbagging. They call KVM immature and the wrong approach.

Calling KVM is immature is, well, premature and misleading. Xen has a headstart of several years. KVM is today not supposed to be in the state Xen is. Nevertheless, KVM already has hardware virt support, SMP support, support for 64-bit host and guests (despite what the article says), live migration, and more.

But immature is not the worst complain. Claiming the hypervisor approach is the only viable option is what should get people worked up.

These are bogus claims. And you have realize where they come from. VMWare’s ESX is a kernel on itself, one which only few people work on (compared to something like Linux). Device drivers will always be a nightmare unless/until devices get their own PCI devices (once DMA can be virtualized). Nevertheless, ESX is a full OS by itself. Plus, ESX has the service console a Linux OS. The service console of course has to have some control over the hypervisor.

For Xen the situation is similar. Here the hypervisor, after the mistakes of the 1.x series, don’t have device drivers included and use a privileged domain, a complete OS.

This means, both Xen and VMWare do not have less code. I’d say they even have more code that is part of the privileged code base. Certainly a Linux installation hosting KVM domains can be scaled down to only have the kernel, kqemu, and the service console…

Read the whole post at source.

Thanks to Fraser Campbell for the news.