Enabling KVM Virtualization for Raspberry Pi 2 (blog.flexvdi.es)

Sorry, we've underestimated the attention this post was going to get. We've just assigned more resources to that machine.

Let's hope that'll be enough to bear with the warm, warm hug of Hacker News ;-)

text version: http://webcache.googleusercontent.com/search?q=cache:ZE1-Hy1...

It's probably not meant about performance, but more along the lines of "now you can use every feature it has".

The overhead can be very small, but the overhead is besides the point. The point is that it for example allows you to run things in parallel that you otherwise would need to reboot to run. E.g. testing a different OS or distribution.

Of course, a virtualized Guest will have a performance penalty.

With that phrase I meant that, following this guide, you can make use of the Virtualization Extensions from the Cortex-A7 which powers the Raspberry Pi 2.

This is pretty useful for running multiple isolated services (such as a media server and an ownCloud instance), doing some kernel hacking, or testing a variety of ARMv7 distributions.

This virtualisation is just for running ARM guests, so you can't run Windows.

There will apparently be an ARM version of Windows 10 for the pi, but that's a cut down version for internet of things type apps.

You can emulate x86 on ARM with something like QEMU. But the performance wouldn't be good enough for any modern OS.

The author does restrict which core the guest can run on, with a patch to qemu. And the guest is limited to a single CPU/core (-smp 1).

Hmm. Could be the mailbox communication for VPU<->CPU communication timing out? BCM should be able to repro and fix that. They could also be able to make enabling HYP mode less of a hack.

As for the lack of an accessible GIC, the VPU runs ThreadX, which has a software timer infrastructure: no reason I can see they couldn't expose those if they wanted.

This ends up really useful if you want to run a different operating system at the same time. It might make it possible to run Windows RT and Linux at the same time on the RPi2 (or as the author is wanting, NetBSD and Linux). This is something that cannot be done by a container system. For practical setups though, you are correct you'll get a better experience with the lower overhead of a container system and likely better support. Being able to work around the hardware issue on the RPi2 though to enable this is something I didn't think was really doable. Congrats to the author, this is a really great development.