To build Marlin 2.0 you'll need [Arduino IDE 1.9](https://www.arduino.cc/en/main/software) or [PlatformIO](http://docs.platformio.org/en/latest/ide.html#platformio-ide). We've posted detailed instructions on how to [build Marlin 2.0 for ARM](http://marlinfw.org/docs/basics/install_arm.html).
Marlin 2.0 adds a new abstraction layer so that Marlin can build and run on 32-bit boards while still retaining full 8-bit AVR compatibility. In this way, features can be enhanced for more powerful platforms while still supporting AVR, whereas splitting up the code would make it harder to maintain and keep everything in sync.
Proposed patches should be submitted as a Pull Request against the ([bugfix-2.0.x](https://github.com/MarlinFirmware/Marlin/tree/bugfix-2.0.x)) branch.
Marlin is published under the [GPL license](/LICENSE) because we believe in open development. The GPL comes with both rights and obligations. Whether you use Marlin firmware as the driver for your open or closed-source product, you must keep Marlin open, and you must provide your compatible Marlin source code to end users upon request. The most straightforward way to comply with the Marlin license is to make a fork of Marlin on Github, perform your modifications, and direct users to your modified fork.
While we can't prevent the use of this code in products (3D printers, CNC, etc.) that are closed source or crippled by a patent, we would prefer that you choose another firmware or, better yet, make your own.
