rsjudge17 / tock

A secure embedded operating system for Cortex-M based microcontrollers

Tock Embedded OS

Tock is an operating system designed for running multiple concurrent, mutually distrustful applications on Cortex-M based embedded platforms. Tock's design centers around protection, both from potentially malicious applications and from device drivers. Tock uses two mechanisms to protect different components of the operating system. First, the kernel and device drivers are written in Rust, a systems programming language that provides compile-time memory safety, type safety and strict aliasing. Tock uses Rust to protect the kernel (e.g. the scheduler and hardware abstraction layer) from platform specific device drivers as well as isolate device drivers from each other. Second, Tock uses memory protection units to isolate applications from each other and the kernel.

Requirements

1. Rust (nightly)
2. arm-none-eabi toolchain (version >= 4.9)
3. stormloader (recommended) or JLinkExe for programming the storm
4. Command line utilities: wget, sed, make

Installing Requirements

Rust (nightly)

We are using rustc 1.12.0-nightly (54c0dcfd6 2016-07-28). We recommand installing it with rustup so you can manage multiple versions of Rust and continue using stable versions for other Rust code:

$ curl https://sh.rustup.rs -sSf | sh

Then override the default version of Rust to use for Tock by running the following from the top-level Tock directory:

$ rustup override set nightly-2016-07-29

arm-none-eabi toolchain

We are currently using arm-none-eabi-gcc version 5.4 from the gcc-arm-embedded PPA on lauchpad. Using pre-5.0 versions from that repo, or other versions packaged with a newlib version earlier than 2.3 will run into problems with missing ARM intrinsics (e.g., __aeabi_memclr).

On Mac OS X, you can get the arm-none-eabi toolchain via port:

$ port install arm-none-eabi-gcc

or via homebrew:

$ brew tap PX4/homebrew-px4
$ brew update
$ brew install gcc-arm-none-eabi

On Linux we recommend getting packages from Launchpad

https://launchpad.net/gcc-arm-embedded/+download

E.g.:

$ curl https://launchpad.net/gcc-arm-embedded/5.0/5-2016-q2-update/+download/gcc-arm-none-eabi-5_4-2016q2-20160622-linux.tar.bz2

On Arch Linux the arm-none-eabi package in pacman contains a sufficiently up to date version of newlibc.

For Windows and other operating systems, download site is here.

Alternatively, if you would like simulator mode in arm-none-eabi-gdb, you can use the build scripts in the tools directory, in this order: build-arm-binutils then build-arm-gcc then build-arm-gdb.

Building the Kernel

If all the tools are in your $PATH, you should be good to go. Otherwise set the env variables:

• RUSTC - rustc compiler
• CC - arm-none-eabi-gcc
• OBJCOPY - arm-none-eabi-objcopy

The build system respects the environment variable TOCK_PLATFORM, which currently defaults to the storm platform but can be set to any available platform (anything in src/platform).

Invoking make in the root directory will build the tock kernel (placing it in tock/build/$(TOCK_PLATFORM)/kernel.o).

Building apps

To build applications, change to apps/$(APP)/ directory and invoke make. This will build the app and generate a binary in Tock Binary Format (using the elf2tbf utility) in build/$(PLATFORM)/$(APP)/$(APP).bin. Depending on the platform, this binary should either be programmed separately from the kernel, or linked into it directly and programmed together. See the README file in each platform subdirectory for details.