Java VMs that do not require an operating system?

Question

I know that BEA was working on LiquidVM which didn't require an underlying operating system, but would like to know if anyone in the open source community is working on something similar.

Ideally I would like to find an implementation where the VM is directly loaded by the OS boot loader.

Answer 1

Unlike SANOS, the JNode operating system is a full operating system with many supported devices, file systems, a network stack, a GUI stack, a command shell and 50 or so commands, and much more. JNode currently runs on x86 (32 bit) with one processor enabled, but x86-64 and multi-processor versions are in development. (JNode is 99.99% Java. Porting to a new architecture would entail rewriting the 0.01% of code that is in assembler, creating / modifying hardware specific drivers ... and writing a native code compiler for the new architecture.)

We currently have ~7 active developers, but we are always looking for new people to join the team, especially people who understand Java AND code generation, garbage collectors, drivers and so on.

(And for what it is worth, we use a recent version of the OpenJDK class libraries: 1.6u24 at the last count.)

Answer 2

There is the Sun project Squawk which a VM that runs on hardware instead of an underlying OS. Useful for embedded devices like the Sun SPOT where Squawk is the OS.

Squawk is licenced under GPLv2.