GNU libc maintainer criticizes Xen and VMware ESX Server hypervisors architectures

In March 2007 Ulrich Drepper, the GNU libc maintainer, was defending KVM project against immaturity claims.

One day before VMware IPO he’s back again on the topic, this time severely criticizing Xen / ESX Server hypervisor architectures (which implies criticizing upcoming Microsoft codename Viridian architecture as well):

People are starting to realize how broken the Xen model is with its privileged Dom0 domain. But the actions they want to take are simply ridiculous: they want to add the drivers back into the hypervisor. There are many technical reasons why this is a terrible idea. You’d have to add (back, mind you, Xen before version 2 did this) all the PCI handling and lots of other lowlevel code which is now maintained as part of the Linux kernel. This would of course play nicely into Xensource’s (the company) pocket. Their technical people so far turn this down but I have no faith in this group: sooner or later they want to be independent of OS vendors and have their own mini-OS in the hypervisor. Adios remaining few advantages of the hypervisor model. But this is of course also the direction of VMWare who loudly proclaim that in the future we won’t have OS as they exist today. Instead only domains with mini-OS which are ideally only hooks into the hypervisor OS where single applications run…

Drepper is employed by Red Hat, which is integrating Xen in its distribution for a long time, but recently stopped mentioning the term Xen at all. Now that XenSource, employing many Xen developers, has been acquired by Citrix, Red Hat may find difficult to still stick with Xen.

Is Drepper offering persuasive argumentations to make his employer switch to KVM?

Ulrich Drepper is not the only open source code guru against virtualization players: yesteday it emerged that also Christopher Helwig, Linux SCSI storage maintainer, is openly against VMware ESX Server, considering the hypervisor a violation of GPL license.

Thanks to OSNews for the news.