Nebulet

What is Nebulet?

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.

Building & Running

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