> I meant running Minix or other toy/research OS under a hypervisor like XEN or KVM that supports IOMMU so Minix could manage a piece of the real hardware like a network card. Such OS can implement complex network protocols or WIFI drivers isolating the rest of the system from bugs there.
Ok, got your point. That certainly makes sense and if for example you think about VFIO coming from the Cisco folks it does not take much imagination why those folks were motivated to do that work since instead of porting their various routing OSes to various hardware platforms just take Linux with KVM and hand control of the networking hardware to the routing OS. That sidesteps the whole GPL issue and isolates the routing OS from the boring hardware bits.
> I hope such setups would be more widespread allowing once again small teams or even a single person to try new OS ideas against latest hardware.
I think it is already happening. I would be hard pressed to name a OS that does not run on VMWare, i.e. Haiku, the Hurd and Minix all run on top of it. Even OS/2 Warp and later is a supported configuration, but I might have thought about some earlier OS/2 releases which IIRC did some strange things in ring 2, but I am too tired to research it at this time.
I am not sure about the quality of those OSes running on top of say VMWare since I recall strange stability issues with FreeBSD 8.3 on some ESXi targets for example, but that is a different problem. Jump five years ahead and I cannot imagine anything but the various hypervisors being a mandatory target platform for any research OS out there. IIRC last year's linux.conf.au had a session about using Linux as the L4sec boot loader for example for some ARM target. That just sounds like an insane thing to do unless you think about what it would take to write all those drivers for L4sec I assume :p.