Break up the firmware build into a 'make export' phase for NuttX on a per-board basis, and then a separate per-config phase that allows us to avoid re-building NuttX all the time, and ship more than one firmware config for a given board.

This is a first cut; it builds one firmware for each of FMU and IO.

makefiles/firmware.mk

@@ -0,0 +1,71 @@
+#
+# Generic Makefile for PX4 firmware.
+#
+# Currently this assumes that we're just compiling SRCS
+# and then linking the whole thing together.
+#
+
+#
+# Work out where this file is, so we can find other makefiles in the
+# same directory.
+#
+export PX4_MK_INCLUDE	?= $(dir $(lastword $(MAKEFILE_LIST)))
+
+#
+# Use the linker script from the NuttX export
+#
+LDSCRIPT		 = $(WORK_DIR)/nuttx-export/build/ld.script
+
+#
+# Add directories from the NuttX export to the relevant search paths
+#
+INCLUDE_DIRS		+= $(WORK_DIR)/nuttx-export/include
+LIB_DIRS		+= $(WORK_DIR)/nuttx-export/libs
+LIBS			+= -lapps -lnuttx
+
+#
+# Things that, if they change, might affect everything
+#
+GLOBAL_DEPS		+= $(MAKEFILE_LIST)
+
+#
+# Include the platform configuration
+#
+include $(PX4_MK_INCLUDE)/$(PLATFORM).mk
+
+#
+# What we're going to build
+#
+PRODUCT_BIN		 = $(WORK_DIR)/firmware.bin
+PRODUCT_SYM		 = $(WORK_DIR)/firmware.sym
+PRODUCTS		 = $(PRODUCT_BIN) $(PRODUCT_SYM)
+
+.PHONY:			all
+all:			$(PRODUCTS)
+
+#
+# Rules for building objects
+#
+OBJS			 = $(foreach src,$(SRCS),$(WORK_DIR)/$(src).o)
+
+$(filter %.c.o,$(OBJS)): $(WORK_DIR)/%.c.o: %.c
+	@echo compile $<
+	@mkdir -p $(dir $@)
+	$(call COMPILE,$<,$@)
+
+$(filter %.cpp.o,$(OBJS)): $(WORK_DIR)/%.cpp.o: %.cpp
+	@mkdir -p $(dir $@)
+	$(call COMPILEXX,$<,$@)
+
+$(filter %.S.o,$(OBJS)): $(WORK_DIR)/%.S.o: %.S
+	@mkdir -p $(dir $@)
+	$(call ASSEMBLE,$<,$@)
+
+-include $(DEP_INCLUDES)
+
+$(PRODUCT_BIN):		$(PRODUCT_SYM)
+	$(call SYM_TO_BIN,$<,$@)
+
+$(PRODUCT_SYM):		$(OBJS) $(GLOBAL_DEPS) $(LINK_DEPS)
+	$(call LINK,$@,$(OBJS))
+

makefiles/gnu-arm-eabi.mk

@@ -0,0 +1,177 @@
+#
+# Definitions for a generic GNU ARM-EABI toolchain
+#
+
+CROSSDEV		 = arm-none-eabi-
+
+CC			 = $(CROSSDEV)gcc
+CXX			 = $(CROSSDEV)g++
+CPP			 = $(CROSSDEV)gcc -E
+LD			 = $(CROSSDEV)ld
+AR			 = $(CROSSDEV)ar rcs
+NM			 = $(CROSSDEV)nm
+OBJCOPY			 = $(CROSSDEV)objcopy
+OBJDUMP			 = $(CROSSDEV)objdump
+
+# XXX this is pulled pretty directly from the fmu Make.defs - needs cleanup
+
+MAXOPTIMIZATION		 = -O3
+
+# base CPU flags
+ARCHCPUFLAGS_CORTEXM4F	 = -mcpu=cortex-m4 \
+			   -mthumb \
+			   -march=armv7e-m \
+			   -mfpu=fpv4-sp-d16 \
+			   -mfloat-abi=hard
+
+ARCHCPUFLAGS_CORTEXM4	 = -mcpu=cortex-m4 \
+			   -mthumb \
+			   -march=armv7e-m \
+			   -mfloat-abi=soft
+
+ARCHCPUFLAGS_CORTEXM3	 = -mcpu=cortex-m3 \
+			   -mthumb \
+			   -march=armv6-m \
+			   -mfloat-abi=soft
+
+ARCHCPUFLAGS		 = $(ARCHCPUFLAGS_$(CONFIG_ARCH))
+
+# optimisation flags
+ARCHOPTIMIZATION	 = $(MAXOPTIMIZATION) \
+			   -fno-strict-aliasing \
+			   -fno-strength-reduce \
+			   -fomit-frame-pointer \
+   			   -funsafe-math-optimizations \
+   			   -fno-builtin-printf \
+   			   -ffunction-sections \
+   			   -fdata-sections
+ifeq ("${CONFIG_DEBUG_SYMBOLS}","y")
+ARCHOPTIMIZATION	+= -g
+endif
+
+# enable precise stack overflow tracking
+# note - requires corresponding support in NuttX
+INSTRUMENTATIONDEFINES	 = -finstrument-functions \
+			   -ffixed-r10
+
+ARCHCFLAGS		 = -std=gnu99
+ARCHCXXFLAGS		 = -fno-exceptions -fno-rtti -std=gnu++0x
+ARCHWARNINGS		 = -Wall \
+			   -Wextra \
+			   -Wdouble-promotion \
+			   -Wshadow \
+			   -Wfloat-equal \
+			   -Wframe-larger-than=1024 \
+			   -Wpointer-arith \
+			   -Wlogical-op \
+			   -Wmissing-declarations \
+			   -Wpacked \
+			   -Wno-unused-parameter
+#   -Wcast-qual  - generates spurious noreturn attribute warnings, try again later
+#   -Wconversion - would be nice, but too many "risky-but-safe" conversions in the code
+#   -Wcast-align - would help catch bad casts in some cases, but generates too many false positives
+
+ARCHCWARNINGS		 = $(ARCHWARNINGS) \
+			   -Wbad-function-cast \
+			   -Wstrict-prototypes \
+			   -Wold-style-declaration \
+			   -Wmissing-parameter-type \
+			   -Wmissing-prototypes \
+			   -Wnested-externs \
+			   -Wunsuffixed-float-constants
+ARCHWARNINGSXX		 = $(ARCHWARNINGS)
+
+# pull in *just* libm from the toolchain ... this is grody
+LIBM			 = $(shell $(CC) $(ARCHCPUFLAGS) -print-file-name=libm.a)
+EXTRA_LIBS		+= $(LIBM)
+
+CFLAGS			 = $(ARCHCFLAGS) \
+			   $(ARCHCWARNINGS) \
+			   $(ARCHOPTIMIZATION) \
+			   $(ARCHCPUFLAGS) \
+			   $(ARCHINCLUDES) \
+			   $(INSTRUMENTATIONDEFINES) \
+			   $(ARCHDEFINES) \
+			   $(EXTRADEFINES) \
+			   -fno-common
+
+CXXFLAGS		 = $(ARCHCXXFLAGS) \
+			   $(ARCHWARNINGSXX) \
+			   $(ARCHOPTIMIZATION) \
+			   $(ARCHCPUFLAGS) \
+			   $(ARCHXXINCLUDES) \
+			   $(INSTRUMENTATIONDEFINES) \
+			   $(ARCHDEFINES) \
+			   $(EXTRADEFINES)
+
+CPPFLAGS		 = $(ARCHINCLUDES) \
+			   $(INSTRUMENTATIONDEFINES) \
+			   $(ARCHDEFINES) \
+			   $(EXTRADEFINES)
+
+AFLAGS			 = $(CFLAGS) -D__ASSEMBLY__
+
+LDFLAGS			+= --warn-common \
+			   --gc-sections \
+			   -T $(LDSCRIPT) \
+			   $(addprefix -L,$(LIB_DIRS))
+
+LIBGCC			:= $(shell $(CC) $(ARCHCPUFLAGS) -print-libgcc-file-name)
+
+
+# files that the final link depends on
+# XXX add libraries that we know about here...
+LINK_DEPS		+= $(LDSCRIPT)
+
+# files to include to get automated dependencies
+DEP_INCLUDES		 = $(subst .o,.d,$(OBJS))
+
+ifeq ($(V),)
+Q			 = @
+else
+Q			 =
+endif
+
+# compile C source $1 to object $2
+# as a side-effect, generate a dependency file
+define COMPILE
+	@echo "CC: $1"
+	$(Q) $(CC) -MD -c $(CFLAGS) $(abspath $1) -o $2
+endef
+
+# compile C++ source $1 to $2
+# as a side-effect, generate a dependency file
+define COMPILEXX
+	@echo "CXX: $1"
+	$(Q) $(CXX) -MD -c $(CXXFLAGS) $(abspath $1) -o $2
+endef
+
+# assemble $1 into $2
+define ASSEMBLE
+	@echo "AS: $1"
+	$(Q) $(CC) -c $(AFLAGS) $(abspath $1) -o $2
+endef
+
+# produce partially-linked $1 from files in $2
+define PRELINK
+	@echo "PRELINK: $1"
+	$(Q) $(LD) -Ur -o $1 $2 && $(OBJCOPY) --localize-hidden $1
+endef
+
+# update the archive $1 with the files in $2
+define ARCHIVE
+	@echo "AR: $2"
+	$(Q) $(AR) $1 $2
+endef
+
+# Link the objects in $2 into the binary $1
+define LINK
+	@echo "LINK: $1"
+	$(Q) $(LD) $(LDFLAGS) -o $1 --start-group $(LIBS) $(EXTRA_LIBS) $(LIBGCC) --end-group
+endef
+
+# convert $1 from a linked object to a raw binary
+define SYM_TO_BIN
+	@echo "BIN: $2"
+	$(Q) $(OBJCOPY) -O binary $1 $2
+endef

makefiles/px4fmu.mk

@@ -0,0 +1,10 @@
+#
+# Platform-specific definitions for the PX4FMU
+#
+
+#
+# Configure the toolchain
+#
+CONFIG_ARCH			 = CORTEXM4F
+
+include $(PX4_MK_INCLUDE)/gnu-arm-eabi.mk

makefiles/px4fmu_default.mk

@@ -0,0 +1,7 @@
+#
+# Makefile for the px4fmu_default configuration
+#
+
+SRCS		 = $(PX4BASE)/platforms/empty.c
+
+include $(PX4BASE)/makefiles/firmware.mk

makefiles/px4io.mk

@@ -0,0 +1,10 @@
+#
+# Platform-specific definitions for the PX4IO
+#
+
+#
+# Configure the toolchain
+#
+CONFIG_ARCH			 = CORTEXM3
+
+include $(PX4_MK_INCLUDE)/gnu-arm-eabi.mk

makefiles/px4io_default.mk

@@ -0,0 +1,7 @@
+#
+# Makefile for the px4io_default configuration
+#
+
+SRCS		 = $(PX4BASE)/platforms/empty.c
+
+include $(PX4BASE)/makefiles/firmware.mk

platforms/empty.c

@@ -0,0 +1,3 @@
+/*
+ * This is an empty C source file, used when building default firmware configurations.
+ */