As I wrote on my previous post, Enabling HYP mode on the Raspberry Pi 2, the newest machine from the Raspberry Pi Foundation features a Cortex-A7 with Virtualization Extensions, but it isn’t possible to make use of such feature out of the box.
In that article I showed that it was possible to start the kernel in HYP mode. Now, I’ll cover the rest of steps needed for enabling KVM virtualization and running your first guest OS.
The newest iteration of the wonderful machine designed by Raspberry Pi Foundation, the Raspberry Pi 2, sports a Broadcom BCM2836 SoC, with four Cortex-A7 cores. The Cortex-A7, being the little brother Cortex-A15, features the ARM Virtualization Extensions, so both Xen and KVM based virtualization should work on it.
At this point, you probably are wondering why would someone want to use virtualization on a RPi2. In addition to the usual “because you can!” answer, there’s a pretty good reason for it. Imagine you want to use the RPi2 as a media center and, at the same time, you want to run some personal services (like ownCloud or Pydio) on it. Instead of polluting the media center image, you can run an isolate, secure, virtual machine for such purpose. And, using my VEXPRESS_KVM port, you can even provide those services running NetBSD! ;-)
This past Halloween, Alan Cox announced Fuzix OS, a project for building a UNIX-like operating system for 8 bit computers, based on UZI sources. This OS targets a number of physical machines, both old and homebrew computers, and some emulators too.
The easiest and more approachable way for trying Fuzix OS is running it on cpmsim, which comes bundled inside the Z80pack package. If want to give it a try the easy way, just continue reading.
UPDATE: Mikolas has added support for the DE2-70 board. Check his repo here: https://github.com/mikolas/socz80-de0_nano
Due to my intrinsic, chronic curiosity, for a long time I wanted to get a in touch with FPGA and related technologies (Verilog, VHDL, etc…), and experience the feeling of total control, having both hardware and software subdued to my control (well, not so much, due to the mysterious and semi-secret process of synthetization and fitting done by the tools involved in the process, but you get the idea).
Some time ago, ARM Holdings presented the new virtualization extensions for its processor architecture, which are now present on some models of the Cortex family, like the Cortex-A7 and Cortex-A15. Though it’s a quite recent technology, both KVM and Xen hypervisors already support such extensions, allowing to run virtualized Guests in the same way you can already do on x86.
It’s true that current SoCs (System-on-Chip) and development boards doesn’t provide a number of cores and RAM memory that invite to run a significant number of Guests on them, but these are the first steps towards stabilization of ARM virtualization, paving the way for the future server-oriented ARM processors. On the other hand, this is also an interesting option for running alternative operating systems (like the *BSD family) on ARM hardware, without dealing with the extremely heterogeneous nature of it.
UPDATE (17/09/14): Some time after writing this, I’ve replaced the QEMU repository referenced here with a clean one without the changes needed for running RISCOS. I’ve just created another repository with the proper sources: https://github.com/slp/qemu-riscos.
Some time ago, while trying to get NetBSD to run on Efika MX Smartbook (I should write about that), I’ve decided that I would never do any serious OS development on a platform without a JTAG interface, or a working emulator. Being able to stop the execution at will, for looking at the CPU registers, or examining an arbitrary memory location, will save you a lot of hours otherwise invested in a painful trial and error cycle.
