Hi everyone,

It's been a while since I've looked at this repository.

Nebulet is not in active development, and hasn't been for a bit more than a year. There are a few reasons for this, but the main one is that I felt it had fulfilled its purpose: to demonstrate that microkernels that run managed code in kernel-mode are viable (before spectre/meltdown ruined things), at least to some extent. (Additionally, it helped me get internships, jobs, etc)

As it stands right now, I don't have the time or the motivation to work on Nebulet. My interests have moved on to other things, primarily the space industry (please message me [email in profile] if anyone who reads this works in the space industry, looking for internships/co-ops).

If someone would like to take on the Nebulet banner and continue to work on it, I'd be happy to pass it on. Otherwise, it'll probably sit here for the foreseeable future and will likely be archived at some point.

- Lachlan Sneff

Nebulet is a Google Summer of Code project started during the summer of 2018. More details about Nebulet and GSoC are here.

Under the hood, Nebulet is a microkernel that executes WebAssembly modules in ring 0 and a single address space to increase performance. This allows for low context-switch overhead, syscalls just being function calls, and exotic optimizations that simply would not be possible on conventional operating systems. The WebAssembly is verified, and due to a trick used to optimize out bounds-checking, unable to even represent the act of writing or reading outside its assigned linear memory.

The Cranelift compiler is used to compile WebAssembly to native machine code. Once compiled, there are no complex interactions between the application and the runtime (unlike jit compilers, like v8) to reduce surface area for vulnerabilities.

Right now, Nebulet isn't ready to do anything yet, but it'll get there.

MacOS requires you to first cross compile binutils and to add the newly compiled ld-bfd to your path.

# checkout code and associated submodules
$> git clone https://github.com/nebulet/nebulet.git
$> cd nebulet/ && rustup override set nightly

# install tools
# make sure that `python` is accessible.
$> rustup component add rust-src
$> rustup target add wasm32-unknown-unknown
$> cargo install cargo-xbuild
$> cargo install --git https://github.com/nebulet/bootimage --branch packaging

# build userspace
$> cargo userspace

# compile the kernel
$> bootimage build --release

# compile and run the kernel in qemu
$> bootimage run --release -- -serial stdio