[Animats]

It's too bad that x86 hardware doesn't do virtualization as well as IBM hardware. You can't stack VMs. That's exactly what's needed here - a non-kernel VM that runs above NT but below the application.

[pmalynin]

You can have nested VMs.

https://www.kernel.org/doc/Documentation/virtual/kvm/nested-...

[overgryphon]

Windows also now supports nested virtualization.

https://msdn.microsoft.com/en-us/virtualization/hyperv_on_wi...

[geofft]

I thought that a) the conclusion of VMware's "Comparison of techniques" paper [1] was that x86 and possibly everything is Popek-and-Goldberg-virtualizable [2] via binary translation, and b) the last several years of Intel and AMD chips all have hardware virtualization support, including nested virtualization, that made their architectures Popek-and-Goldberg-virtualizable in the obvious way?

[1] https://www.vmware.com/pdf/asplos235_adams.pdf

[2] https://en.wikipedia.org/wiki/Popek_and_Goldberg_virtualizat...

[pjmlp]

Looking at the way mainframes work, with their higher level languages, JIT compilers at kernel level, object databases, type 1 hypervisors, ....

It is quite interesting to see mainstream OSes increasingly get adopting all those features.

[Animats]

Very, very slowly. Microprocessors still have DMA instead of mainframe-like "channels", although we're starting to see MMUs on the I/O side. With channels, devices can't blither all over memory and neither driver nor device need be trusted.