RISC OS and NetBSD running on same SoC

I have been experimenting with running two systems at the same time on the RK3399 SoC.

It all begun when I figured out how to switch to the A72 cpu for RISC OS. When the switch was done, the A53 cpu just continued to execute code.

OK I thought why not give it something to do!

My first step was to run some small programs.

It worked.

The second thing was switching that cpu to aarch32 and launch RISC OS on that cpu.

It worked quite well, but I can't really see the meaning on running two RISC OSes.

I decided that NetBSD would be the ideal system to run.

Technical details:

As mentioned the system boots up at the same time.

Some units in the SoC needs to be shared, most important the GIC. With GIC I do config it in RISC OS and give affinity to NetBSD for some devices.

The console is based on simplefb, and stores its framebuffer at a fixed physical address. My RISC OS client polls that area and create a sprite (RISC OS native bitmap format) with that area as buffer.

The keyboard works with another shared area. When a key is pressed in RISC OS I look up the scancode and write that to the keyboard RAM area.

Currently most normal keys , and shift key works. I would expect to have all mod keys working pretty soon.

Screenshot of X11 running DWM,xterm and Xemacs: