This is a fork from arduino/ArduinoCore-samd on GitHub. This will be used to maintain Arduino support for SAM D|L|C (M0+ and M4F) boards including the MattairTech Xeno Mini and the MT-D21E (see https://www.mattairtech.com/). It adds support for new devices like the D51, L21, C21, and D11. It also adds new clock sources, like a high speed crystal or internal oscillator.
This corrects the include path for the CMSIS-Atmel inside the MattairTech package. Without this correction the bootloader compilation fails.