git subrepo clone https://github.com/libopencm3/libopencm3

subrepo:
  subdir:   "libopencm3"
  merged:   "f5813a54"
upstream:
  origin:   "https://github.com/libopencm3/libopencm3"
  branch:   "master"
  commit:   "f5813a54"
git-subrepo:
  version:  "0.4.3"
  origin:   "???"
  commit:   "???"

libopencm3/mk/README

@@ -0,0 +1,121 @@
+-------------------------------------------------------------------------------
+README
+-------------------------------------------------------------------------------
+
+  This directory contains makefile modular support files, that can be used in
+your project.
+
+  Each module is packaged with two inclusion makefiles, <module>-config.mk and
+<module>-rules.mk. The first one defines some new variables for the make, or
+appends values to the existing variables for the make. The second defines rules
+for support building.
+
+  So in your project, the <module>-config.mk should be included at some place,
+where you are defining variables (near the beginning of the file), and file
+<module>-rules.mk should be included in the rules part of makefile (somewhere
+near to the end of file).
+
+Example makefile using the gcc compiler module together with the linker script
+generator module:
+
+>>>>>>
+DEVICE          =
+OPENCM3_DIR     =
+OBJS            += foo.o
+
+CFLAGS          += -Os -ggdb3
+CPPFLAGS	+= -MD
+LDFLAGS         += -static -nostartfiles
+LDLIBS          += -Wl,--start-group -lc -lgcc -lnosys -Wl,--end-group
+
+include $(OPENCM3_DIR)/mk/genlink-config.mk
+include $(OPENCM3_DIR)/mk/gcc-config.mk
+
+.PHONY: clean all
+
+all: binary.elf binary.hex
+
+clean:
+	$(Q)$(RM) -rf binary.* *.o
+
+include $(OPENCM3_DIR)/mk/genlink-rules.mk
+include $(OPENCM3_DIR)/mk/gcc-rules.mk
+<<<<<<
+
+
+MODULES
+=======
+
+-------------------------------------------------------------------------------
+gcc
+-------------------------------------------------------------------------------
+
+  This module adds an extended support for GCC toolchain. This adds rules,
+necessary for compiling C and C++ files into elf binary, and rules for
+generation of bin, hex, or srec output files for flashing.
+
+Variables to control the build process (should be set in your makefile):
+------------------------------------------------------------------------
+
+CFLAGS		C compiler flags
+CXXFLAGS	C++ compiler flags
+CPPFLAGS	C preprocessor flags (used for C and for C++ compiler)
+LDFLAGS		Linker flags
+ARCH_FLAGS	Architecture specification flags (-mcpu, -march etc )
+
+Variables to tell gcc about project dependencies and input files
+----------------------------------------------------------------
+
+LDSCRIPT	Linker script file name (can be generated or fixed)
+LIBDEPS		Array of library filenames that shoud be rebuilt if needed
+LDLIBS		Array of libraries to be linked with (array of -l<libname>)
+OBJS		Array of object files to be built
+
+
+-------------------------------------------------------------------------------
+genlink
+-------------------------------------------------------------------------------
+
+  This module adds an support for the user to the linker script generator. The
+linker script will be generated as the file $(DEVICE).ld in the project folder,
+and automatically be used for the linking process.
+Additionally the matching library is added to the LDLIBS variable.
+
+Variables to control the build process (should be set in your makefile):
+------------------------------------------------------------------------
+
+DEVICE		The full device part name used for the compilation process.
+OPENCM3_DIR	The root path of libopencm3 library.
+
+Output variables from this module:
+----------------------------------
+
+CPPFLAGS		(appended)
+ - Appends the chip family to the CPPFLAGS. For example -DSTM32F1
+ - Appends the include path for libopencm3
+
+ARCH_FLAGS	(replaced)
+ - Architecture build flags for specified chip.
+ * No needed to handle this variable if you use module <gcc> too.
+
+LDSCRIPT	(replaced)
+ - Linker script generated file.
+ * No needed to handle this variable if you use module <gcc> too.
+
+LDLIBS (appended)
+ - LDLIBS += -lopencm3_$(family) is appended to link against the
+   matching library.
+
+LDFLAGS (appended)
+ - LDFLAGS += -L$(OPENCM3_DIR)/lib is appended to make sure the
+   matching library can be found.
+
+family,cpu,fpu (replaced)
+ - these are used internally to create the above variables
+
+Temporary variables that you should not use in your makefile:
+-------------------------------------------------------------
+
+GENLINK_DEFS
+GENLINK_ARCH
+GENLINK_LIB