Older versions of the Silicon Labs 8-bit software development kit (SDK) contained device specific header files (i.e. "C8051Fxxx.h") as well common header files that were referenced and included by the device-specific files (i.e. "compiler_defs.h").  While most current Silicon Labs example code and source files in the C8051/EFM8 SDK are covered solely under the Silicon Labs End User Software License Agreement (http://developer.silabs.com/legal/version/v11/Silicon_Labs_Software_License_Agreement.txt), "compiler_defs.h" contains sections of code which were authored by a third party and are covered by a separate license agreement.

For those wishing to develop their application code using Silicon Labs-provided example code and header files, but wishing to have this code be covered under a single license agreement from Silicon Labs (see link above), we have created a new file called "si_toolchain.h" that supersedes "compiler_defs.h."  In the 8051 SDK, the correct device-specific files to use for C8051 devices are called "SI_C8051Fxxx_SI_defs.h."  Files with this naming convention will reference and include "si_toolchain.h" and will fall exclusively under the Silicon Labs End User Software License Agreement.  These updated files should be available in the Silicon Labs 8051 SDK after April 19, 2017.