Structure build system to build for multiple boards/apps/environments

firmware/README.txt

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+
+== BOARDS
+
+A board defines a given circuit board, i.e. SIMtrace, OWHW, QMOD
+
+It defines the given hardware model for which the program is to be
+compiled.
+
+Current boards supported are:
+* simtrace: The good old Osmocom SIMtrace PCB with SAM3 instead of
+  SAM7, open hardware.
+* qmod: A sysmocom-proprietary quad mPCIe carrier board, publicly available
+* owhw: An undisclosed sysmocom-internal board, not publicly available
+
+== APPLICATIONS
+
+An application is a specific piece of software with given
+functionality.
+
+== ENVIRONMENTS
+
+An environment is a runtime environment, typically defined by a linker
+script.  The current runtime environments include
+* flash: Run natively from start of flash memory
+* dfu: Run after a DFU bootloader from an offset after the first 16k
+  of flash (the first 16k are reserved for the bootloader)
+* ram: Run from within the RAM of the chip, downloaded via JTAG/SWD
+
+
+== Building
+
+A given software build is made for a specific combination of an APP
+running in a certain ENVIRONMENT on a given BOARD.