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The Age of Hypervisors

The science behind Virtual Machine Monitors, or VMM, aka Hypervisors, was demystified almost half a century ago, in a famous ACM publication, “Formal Requirements for Virtualizable Third Generation Architectures”.

In my life, I had the honor of working on some of the most bleeding edge virtualization technologies of their day.  My first was IBM’s VM, VSAM and a host of other v-words.  My last was at XenSource (now Citrix) and Cisco, on what I still think is the most complete hypervisor of our age, true to its theoretical foundation in the Math paper I just mentioned.

Though Xen is arguably the most widely used hypervisor in the Cloud or sum of all servers in the world today, I actually think its most interesting accomplishment lies in what its founders just announced this week.  Therefore, I want to extend my congratulations to my good friends Simon Crosby and Ian Pratt for the admirable work at Bromium with vSentry.

I think it is remarkable for two reasons.  It addresses the missing part of what hypervisors are useful, which is security; for those of you that actually read Popek & Goldberg’s paper, you would note that VMM’s are very good at intercepting not just privileged but also sensitive instructions, and very few people out there, until now have focused on the latter, the security piece.  But there is one more reason, in fact the key point of this paper, the necessary and sufficient conditions for a system to be able to have a VMM or hypervisor, and I am hoping the Xen guys who have done so well articulating that for real (not fictional or hyped) hypervisors, can also help sort our the hype from fiction in what is ambiguously called nowadays a “network hypervisor”.

Could this approach be what is actually missing, to sort out truth from hype in what we call SDN today?  Is this the new age of hypervisors?  Or is this just another useful application of an un-hyped hypervisor?

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