pixhawk make文件分析

由于笔者没学过Linux等系统，对make文件所知甚少，本节分析可能有大量错误，只提供参考，随着技术积累，以后会回过头改正错误的地方，也非常欢迎提出指导意见。

其中分析大多数参考网上解释，加上自己的理解，对make源码逐行阅读并做了相关注释和分析。

统一规定：红字是注释分析；代码部分左边是程序，右边是注释。

下面开始分析

首先打开ardupilot/Arducopter/makefile

include ../mk/apm.mk  

引用其他mk所以去看看apm.mk是什么

# find the mk/ directory, which is where this makefile fragment# lives. (patsubst strips the trailing slash.)SYSTYPE:=$(shell uname)     系统环境是win还是Linux？

下述程序是为了根据系统的类型确定不同的工作目录MK_DIR

我们始终需要记住一件事，那就是我们在哪个目录编译，以及我们的编译命令。编译目录为： ardupilot/ArduCopter，编译命令我们用的是“make px4”，但我们也可以改变命令编译我们需要的。

ifneq ($(findstring CYGWIN, $(SYSTYPE)),)   ifeq (<arg1>, <arg2>)比较参数“arg1”和“arg2”的值是否相同，  (判断系统环境是否不为CYGWIN)                      不同为真；ifneq (<arg1>, <arg2>)，相同为真                                    $(findstring find,in)                                      $(findstring a,a b c)  $(findstring a,b c)  结果分别为‘a’ and ‘’MK_DIR := $(shell cygpath -m ../mk)   cygpath用于转换Unix和Windows的格式路径                                      -m, --mixed  like --windows, but with regular slashes (C:/WINNT)                                    -w, --windows         print Windows form of NAMEs (C:\WINNT)elseMK_DIR := $(patsubst %/,%,$(dir $(lastword $(MAKEFILE_LIST)))) $应该是取值的意思         根据gnu make定义，gnu make 会自动将所有读取的makefile路径都会加入到MAKEFILE_LIST变量中，                而且是按照读取的先后顺序添加。例如

#If a makefile named Makefile has this content:name1 := $(lastword $(MAKEFILE_LIST))include inc.mkname2 := $(lastword $(MAKEFILE_LIST))all:        @echo name1 = $(name1)        @echo name2 = $(name2)#then you would expect to see this output:#name1 = Makefile#name2 = inc.mk

格式：$(patsubst ,,)
名称：模式字符串替换函数——patsubst
功能：查找中的单词（单词以“空格”、“Tab”或“回车”“换行”分隔）是否符合模式，如果匹配的话，则以替换。这里，可以包括通配符“%”，表示任意长度的字串。如果中也包含“%”，那么，中的这个“%”将是中的那个“%”所代表的字串。（可以用“\”来转义，以“\%”来表示真实含义的“%”字符）
返回：函数返回被替换过后的字符串。
示例：
$(patsubst %.c,%.o,x.c.c bar.c)
把字串“x.c.c bar.c”符合模式[%.c]的单词替换成[%.o]，返回结果是“x.c.o bar.o”
而dir是提取路径

$(dir src/foo.c hacks)#produces the result ‘src/ ./’.

所以$(patsubst%/,%,$(dir $(lastword $(MAKEFILE_LIST))))返回了当前的mk路径，到这里也就得出了 MK_DIR 信息。

endifinclude $(MK_DIR)/environ.mk     添加environ.mk文件，关键的环境变量在里面实现# short-circuit build for the configure targetifeq ($(MAKECMDGOALS),configure) 如果编译参数是configure，则添加configure.mkinclude $(MK_DIR)/configure.mk    configure.mk的内容为configure:else                                       @echo "make configure is no longer required"                                      所以可以直接执行下面的程序# short-circuit build for the help targetinclude $(MK_DIR)/help.mk         添加help.mk   help.mk的内容主要是打印一些信息，对理解pixhawk程序有点帮助# common makefile components     添加常用makefileinclude $(MK_DIR)/targets.mk     添加targets.mkinclude $(MK_DIR)/sketch_sources.mk    添加sketch_sources.mkifneq ($(MAKECMDGOALS),clean)    判断命令不为clean是否为真# board specific includes         根据板子添加相应的.mk文件ifeq ($(HAL_BOARD),HAL_BOARD_SITL)include $(MK_DIR)/board_native.mkendififeq ($(HAL_BOARD),HAL_BOARD_LINUX)include $(MK_DIR)/board_linux.mkendififeq ($(HAL_BOARD),HAL_BOARD_PX4)include $(MK_DIR)/board_px4.mkendififeq ($(HAL_BOARD),HAL_BOARD_VRBRAIN)include $(MK_DIR)/board_vrbrain.mkendififeq ($(HAL_BOARD),HAL_BOARD_FLYMAPLE)include $(MK_DIR)/board_flymaple.mkendififeq ($(HAL_BOARD),HAL_BOARD_QURT)include $(MK_DIR)/board_qurt.mkendifendifendif

这个时候可能我们会很迷惑， $(HAL_BOARD)的值到底是多少？

    但其实我们在执行“make px4”命令编译的时候会有一行信息：

HAL_BOARD=HAL_BOARD_PX4HAL_BOARD_SUBTYPE= TOOLCHAIN=NATIVEEXTRAFLAGS=-DGIT_VERSION="b6d361a3" -DNUTTX_GIT_VERSION="eba6b56f"-DPX4_GIT_VERSION="cf208916"

这行信息非常清楚地告诉了我们用的是“$(MK_DIR)/board_px4.mk”文件。

所以apm.mk根据各种判断，添加environ.mk文件(关键的环境变量在里面实现), 添加help.mk(打印相关信息)，添加targets.mk，添加sketch_sources.mk，添加board_px4.mk

接下来就分别分析environ.mk，targets.mk，sketch_sources.mk，board_px4.mk

environ.mk  关键的环境变量在里面实现

windows下的环境变量简单来说就是将某些数据，文件或文件夹设置为系统默认值，这样你调用的时候就不用给出完整路径和地址或进行设置，直接用名字就可以了。

这里实现的是查找SKETCHBOOK的位置，根据源文件路径判断SKETCH名称，算出要build的哪里，建立BUILDROOT目录，根据编译参数确定HAL_BOARD类型，等等为系统实现做基础工作。

以下是部分代码分析：

GIT_VERSION := $(shell git rev-parse HEAD | cut -c1-8)   获得git 版本## Locate the sketch sources based on the initial Makefile's path#SRCROOT:=$(realpath $(dir $(firstword $(MAKEFILE_LIST)))) 通过判断是否有libraries来获取当前ifneq ($(findstring CYGWIN, $(SYSTYPE)),)                             make的真实路径，不存在则返回为空  # Workaround a $(realpath ) bug on Cygwin                    libraries下的测试 makefile都是指向apm  ifeq ($(SRCROOT),)    SRCROOT:=$(shell cygpath -m ${CURDIR})    $(warning your realpath function is not working)    $(warning > setting SRCROOT to $(SRCROOT))  endifendif## We need to know the location of the sketchbook.  If it hasn't been overridden,# try the parent of the current directory.  If there is no libraries directory# there, assume that we are in a library's examples directory and try backing up# further.             通过判断是否有libraries来获取当前SKETCHBOOK的位置#                       查找SKETCHBOOK的位置ifeq ($(SKETCHBOOK),) wildcard通配符，如：列出该目录下所有的C文件为$(wildcard *.c)  SKETCHBOOK:=$(shell cd $(SRCROOT)/.. && pwd)   ifeq ($(wildcard $(SKETCHBOOK)/libraries),) 此位置为该项目的根目录    SKETCHBOOK:=$(shell cd $(SRCROOT)/../.. && pwd)  endif  ifeq ($(wildcard $(SKETCHBOOK)/libraries),)    SKETCHBOOK:=$(shell cd $(SRCROOT)/../../.. && pwd)  endif  ifeq ($(wildcard $(SKETCHBOOK)/libraries),)    SKETCHBOOK:=$(shell cd $(SRCROOT)/../../../.. && pwd)  endif  ifeq ($(wildcard $(SKETCHBOOK)/libraries),)    $(error ERROR: cannot determine sketchbook location - please specify on the commandline with SKETCHBOOK=<path>)  endifelse  ifeq ($(wildcard $(SKETCHBOOK)/libraries),)    $(warning WARNING: sketchbook directory $(SKETCHBOOK) contains no libraries)  endifendififneq ($(findstring CYGWIN, $(SYSTYPE)),) 如果是在win平台，转换为win格式的路径    # Convert cygwin path into a windows normal path    SKETCHBOOK:= $(shell cygpath ${SKETCHBOOK})endififneq ($(wildcard $(SKETCHBOOK)/config.mk),) 如果config.mk不是空，include他$(info Reading $(SKETCHBOOK)/config.mk)include $(SKETCHBOOK)/config.mkendififneq ($(wildcard $(SKETCHBOOK)/developer.mk),) 如果developer.mk不是空，include他$(info Reading $(SKETCHBOOK)/developer.mk)include $(SKETCHBOOK)/developer.mkendif## Work out the sketch name from the name of the source directory.#找出是哪个sketch，他的名字SKETCH:=$(lastword $(subst /, ,$(SRCROOT))) 根据源文件路径判断SKETCH名称# Workaround a $(lastword ) bug on Cygwin               subst是将源文件路径中所有的/替换为空格。ifeq ($(SKETCH),)  WORDLIST:=$(subst /, ,$(SRCROOT))  SKETCH:=$(word $(words $(WORDLIST)),$(WORDLIST))Endif## Work out where we are going to be building things#算出哪是我们要build的事TMPDIR?=/tmpifneq ($(findstring px4, $(MAKECMDGOALS)),)# when building px4 we need all sources to be inside the sketchbook directory# as the NuttX build system relies on itBUILDROOT:=$(SKETCHBOOK)/Build.$(SKETCH) 建立BUILDROOT目录：根据编译目标$(MAKECMDGOALS)建Endif                                                    立相关目录，如果编译目标不匹配，建立临时目录。ifneq ($(findstring vrbrain, $(MAKECMDGOALS)),)# when building vrbrain we need all sources to be inside the sketchbook directory# as the NuttX build system relies on itBUILDROOT:=$(SKETCHBOOK)/Build.$(SKETCH)endififneq ($(findstring vrubrain, $(MAKECMDGOALS)),)# when building vrbrain we need all sources to be inside the sketchbook directory# as the NuttX build system relies on itBUILDROOT:=$(SKETCHBOOK)/Build.$(SKETCH)endififneq ($(findstring vrhero, $(MAKECMDGOALS)),)# when building vrbrain we need all sources to be inside the sketchbook directory# as the NuttX build system relies on itBUILDROOT:=$(SKETCHBOOK)/Build.$(SKETCH)Endififneq ($(APPDIR),) # this is a recusive PX4 buildHAL_BOARD = HAL_BOARD_PX4endif# handle target based overrides for board type根据编译参数确定HAL_BOARD类型。ifneq ($(findstring px4, $(MAKECMDGOALS)),) HAL_BOARD = HAL_BOARD_PX4endififneq ($(findstring sitl, $(MAKECMDGOALS)),)HAL_BOARD = HAL_BOARD_SITLHAL_BOARD_SUBTYPE = HAL_BOARD_SUBTYPE_NONEendififneq ($(findstring linux, $(MAKECMDGOALS)),)HAL_BOARD = HAL_BOARD_LINUXHAL_BOARD_SUBTYPE = HAL_BOARD_SUBTYPE_LINUX_NONEendif

board_px4.mk文件代码：

TOOLCHAIN = NATIVEinclude $(MK_DIR)/find_tools.mk        include $(MK_DIR)/px4_targets.mkfind_tools.mk就是寻找编译工具FIND_TOOL    =  $(firstword $(wildcard $(addsuffix /$(1),$(TOOLPATH)))) 快速查找px4_targets.mk部分代码分析NUTTX_GIT_VERSION := $(shell cd $(NUTTX_SRC) && git rev-parse HEAD | cut -c1-8) 获取NUTTX_GIT_VERSIONPX4_GIT_VERSION:= $(shell cd $(PX4_ROOT) && git rev-parse HEAD | cut -c1-8) 及PX4_GIT_VERSION版本EXTRAFLAGS += -DNUTTX_GIT_VERSION="\"$(NUTTX_GIT_VERSION)\""  添加EXTRAFLAGSEXTRAFLAGS += -DPX4_GIT_VERSION="\"$(PX4_GIT_VERSION)\""  = 是最基本的赋值   := 是覆盖之前的值EXTRAFLAGS += -DUAVCAN=1                               ?= 是如果没有被赋值过就赋予等号后面的值                                                        += 是添加等号后面的值PX4_V2_CONFIG_FILE=$(MK_DIR)/PX4/config_px4fmu-v2_APM.mk      更新PX4_V2_CONFIG_FILE配置文件在这里又调用了px4_common.mk，这是一个很重要的东西；如定义了ROMFS_ROOT，定义了BUILTIN_COMMANDS，其中strip为去除空格；SKETCHFLAGS=$(SKETCHLIBINCLUDES) -DARDUPILOT_BUILD -DTESTS_MATHLIB_DISABLE -DCONFIG_HAL_BOARD=HAL_BOARD_PX4 -DSKETCHNAME="\\\"$(SKETCH)\\\"" -DSKETCH_MAIN=ArduPilot_main -DAPM_BUILD_DIRECTORY=APM_BUILD_$(SKETCH)WARNFLAGS = -Wall -Wextra -Wlogical-op -Werror -Wno-unknown-pragmas -Wno-redundant-decls -Wno-psabi -Wno-packed -Wno-error=double-promotion -Wno-error=unused-variable -Wno-error=reorder -Wno-error=float-equal -Wno-error=pmf-conversions -Wno-error=missing-declarations -Wno-error=unused-functionOPTFLAGS = -fsingle-precision-constant定义SKETCHFLAGS/WARNFLAGS/OPTFLAGS，其中-D表示为define，-I为添加库PYTHONPATH=$(SKETCHBOOK)/mk/PX4/Tools/genmsg/src:$(SKETCHBOOK)/mk/PX4/Tools/gencpp/src确定PYTHONPATH路径PX4_MAKE = $(v)+ GIT_SUBMODULES_ARE_EVIL=1 ARDUPILOT_BUILD=1 $(MAKE) -C $(SKETCHBOOK) -f $(PX4_ROOT)/Makefile.make EXTRADEFINES="$(SKETCHFLAGS) $(WARNFLAGS) $(OPTFLAGS) "'$(EXTRAFLAGS)' APM_MODULE_DIR=$(SKETCHBOOK) SKETCHBOOK=$(SKETCHBOOK) CCACHE=$(CCACHE) PX4_ROOT=$(PX4_ROOT) NUTTX_SRC=$(NUTTX_SRC) MAXOPTIMIZATION="-Os" UAVCAN_DIR=$(UAVCAN_DIR)PX4_MAKE_ARCHIVES = $(MAKE) -C $(PX4_ROOT) -f $(PX4_ROOT)/Makefile.make NUTTX_SRC=$(NUTTX_SRC) CCACHE=$(CCACHE) archives MAXOPTIMIZATION="-Os"定义PX4_MAKE及PX4_MAKE_ARCHIVES$(MAKE) –C  表示进入指定文件夹执行$(PX4_ROOT)/Makefile.make  编译PX4原生代码的HASHADDER_FLAGS += --ardupilot "$(SKETCHBOOK)" 添加HASHADDER_FLAGSifneq ($(wildcard $(PX4_ROOT)),)HASHADDER_FLAGS += --px4 "$(PX4_ROOT)"endififneq ($(wildcard $(NUTTX_SRC)/..),)HASHADDER_FLAGS += --nuttx "$(NUTTX_SRC)/.."endifHASHADDER_FLAGS += --uavcan "$(UAVCAN_DIR)".PHONY: module_mkmodule_mk:            生成module_mk$(v) echo "Building $(SKETCHBOOK)/module.mk"$(RULEHDR)$(v) echo "# Auto-generated file - do not edit" > $(SKETCHBOOK)/module.mk.new$(v) echo "MODULE_COMMAND = ArduPilot" >> $(SKETCHBOOK)/module.mk.new$(v) echo "SRCS = $(wildcard $(SRCROOT)/*.cpp) $(SKETCHLIBSRCSRELATIVE)" >>$(SKETCHBOOK)/module.mk.new$(v) echo "MODULE_STACKSIZE = 4096" >> $(SKETCHBOOK)/module.mk.new$(v) echo "EXTRACXXFLAGS = -Wframe-larger-than=1300" >> $(SKETCHBOOK)/module.mk.new$(v) cmp $(SKETCHBOOK)/module.mk $(SKETCHBOOK)/module.mk.new 2>/dev/null || mv $(SKETCHBOOK)/module.mk.new $(SKETCHBOOK)/module.mk$(v) rm -f $(SKETCHBOOK)/module.mk.newpx4-v2: $(BUILDROOT)/make.flags CHECK_MODULES $(MAVLINK_HEADERS)   最后建立px4的相关目标$(PX4_ROOT)/Archives/px4fmu-v2.export $(SKETCHCPP) module_mk px4-io-v2$(RULEHDR)           注意：px4-v2的依赖条件中包含了$(SKETCHCPP)，从这里调用该工程下的源文件；$(v) cp $(PX4_V2_CONFIG_FILE) $(PX4_ROOT)/makefiles/nuttx/   cp  复制copy$(PX4_MAKE) px4fmu-v2_APM$(v) arm-none-eabi-size $(PX4_ROOT)/Build/px4fmu-v2_APM.build/firmware.elf$(v) cp $(PX4_ROOT)/Images/px4fmu-v2_APM.px4 $(SKETCH)-v2.px4$(v) $(SKETCHBOOK)/Tools/scripts/add_git_hashes.py $(HASHADDER_FLAGS) "$(SKETCH)-v2.px4" "$(SKETCH)-v2.px4"$(v) echo "PX4 $(SKETCH) Firmware is in $(SKETCH)-v2.px4"

这个步骤就是编译 px4fmu-v2_APM的过程，仔细分析这段代码

首先通过echo命令将$(xxx)真正意思打印出来，分别用1到7对应起来

echo "1$(BUILDROOT) 2$(MAVLINK_HEADERS) 3$(PX4_ROOT) 4$(PX4_V2_CONFIG_FILE)5$(PX4_MAKE) 6$(SKETCH) 7$(SKETCHBOOK)"1/c/ardupilot/Build.ArduCopter 2/c/ardupilot/Build.ArduCopter/libraries/GCS_MAVLink/include/mavlink/v1.0/ardupilotmega/mavlink.h   3/c/ardupilot/modules/PX4Firmware 4../mk/PX4/config_px4fmu-v2_APM.mk 5@+ GIT_SUBMODULES_ARE_EVIL=1 ARDUPILOT_BUILD=1 make -C /c/ardupilot -f /c/ardupilot/modules/PX4Firmware/Makefile.make EXTRADEFINES=-I/c/ardupilot/libraries/ -I/c/ardupilot/Build.ArduCopter/libraries/ -I/c/ardupilot/Build.ArduCopter/libraries/GCS_MAVLink/ -DARDUPILOT_BUILD -DTESTS_MATHLIB_DISABLE -DCONFIG_HAL_BOARD=HAL_BOARD_PX4 -DSKETCHNAME=\"ArduCopter\" -DSKETCH_MAIN=ArduPilot_main -DAPM_BUILD_DIRECTORY=APM_BUILD_ArduCopter -Wall -Wextra -Wlogical-op -Werror -Wno-unknown-pragmas -Wno-redundant-decls -Wno-psabi -Wno-packed -Wno-error=double-promotion -Wno-error=unused-variable -Wno-error=reorder -Wno-error=float-equal -Wno-error=pmf-conversions -Wno-error=missing-declarations -Wno-error=unused-function -fsingle-precision-constant '-DGIT_VERSION="3c5287e8" -I/c/ardupilot/libraries/AP_Common/missing -DNUTTX_GIT_VERSION="579e82d4" -DPX4_GIT_VERSION="55491083" -DUAVCAN=1 -DHAVE_STD_NULLPTR_T=0 -I/c/ardupilot/Build.ArduCopter/libraries/GCS_MAVLink/include/mavlink' APM_MODULE_DIR=/c/ardupilot SKETCHBOOK=/c/ardupilot CCACHE= PX4_ROOT=/c/ardupilot/modules/PX4Firmware NUTTX_SRC=/c/ardupilot/modules/PX4NuttX/nuttx/ MAXOPTIMIZATION=-Os UAVCAN_DIR=/c/ardupilot/modules/uavcan/ 6ArduCopter 7/c/ardupilot

然后根据脚本的语法，可知主要是$(PX4_MAKE)px4fmu-v2_APM完成编译任务

$(PX4_MAKE)真正意思对应上面第5条，再根据脚本基本语法可知

make-C /c/ardupilot -f /c/ardupilot/modules/PX4Firmware/Makefile.make主要完成编译任务

-D是定义、-I是添加库、=是赋值

由此可定位到/c/ardupilot/modules/PX4Firmware/Makefile.make

但是Makefile.make文件里没有px4fmu-v2_APM的目标，说明目标被处理过了。于是只好去看编译输出信息了

%%%%%%%% Building px4fmu-v2_APM in /c/ardupilot/modules/PX4Firmware/Build/px4fmu-v2_APM.build/%%%%

通过这串信息，匹配到了这样一个目标

## Generate FIRMWARES.#.PHONY: $(FIRMWARES)$(BUILD_DIR)%.build/firmware.px4: config   = $(patsubst $(BUILD_DIR)%.build/firmware.px4,%,$@)$(BUILD_DIR)%.build/firmware.px4: work_dir = $(BUILD_DIR)$(config).build/$(FIRMWARES): $(BUILD_DIR)%.build/firmware.px4:generateuorbtopicheaders checksubmodules@$(ECHO) %%%%@$(ECHO) %%%% Building $(config) in $(work_dir)@$(ECHO) %%%%$(Q) $(MKDIR) -p $(work_dir)$(Q)+ $(MAKE) -r -C $(work_dir) \               从这开始，完成编译工作-f $(PX4_MK_DIR)firmware.mk \               语句尾部“\”表示语句连接CONFIG=$(config) \WORK_DIR=$(work_dir) \$(FIRMWARE_GOAL)$(PX4_MK_DIR)firmware.mk的真正意思是/c/ardupilot/modules/PX4Firmware/makefiles/firmware.mk

这样就定位到firmware.mk文件  此处主要分析px4_targets.mk，firmware.mk文件内容较多，下节再分析。

px4-io-v2: $(PX4_ROOT)/Archives/px4io-v2.export$(v)+ $(MAKE) -C $(PX4_ROOT) -f $(PX4_ROOT)/Makefile.make px4io-v2_default EXTRADEFINES="-DARDUPILOT_BUILD"$(v) cp $(PX4_ROOT)/Images/px4io-v2_default.bin px4io-v2.bin$(v) cp $(PX4_ROOT)/Build/px4io-v2_default.build/firmware.elf px4io-v2.elf$(v) mkdir -p $(MK_DIR)/PX4/ROMFS/px4io/        mkdir  创建目录$(v) cp px4io-v2.bin $(MK_DIR)/PX4/ROMFS/px4io/px4io.bin$(v) mkdir -p $(MK_DIR)/PX4/ROMFS/bootloader/$(v) cp $(SKETCHBOOK)/mk/PX4/bootloader/px4fmuv2_bl.bin $(MK_DIR)/PX4/ROMFS/bootloader/fmu_bl.bin$(v) echo "PX4IOv2 Firmware is in px4io-v2.bin"

实际的内容是make -C /e/ardupilot/modules/PX4Firmware px4io-v2_default 编译firmware基本文件/bin/rm -f px4io-v2.bincp /e/ardupilot/modules/PX4Firmware/Build/px4io-v2_default.build/firmware.bin px4io-v2.bincp /e/ardupilot/modules/PX4Firmware/Images/px4io-v2_default.bin px4io-v2.bincp /e/ardupilot/modules/PX4Firmware/Build/px4io-v2_default.build/firmware.elf px4io-v2.elfmkdir -p ../mk/PX4/ROMFS/px4io/rm -f ../mk/PX4/ROMFS/px4io/px4io.bincp px4io-v2.bin ../mk/PX4/ROMFS/px4io/px4io.binmkdir -p ../mk/PX4/ROMFS/bootloader/rm -f ../mk/PX4/ROMFS/bootloader/fmu_bl.bincp /c/ardupilot/mk/PX4/bootloader/px4fmuv2_bl.bin ../mk/PX4/ROMFS/bootloader/fmu_bl.binPX4IOv2 Firmware is in px4io-v2.bin生成.bin .elf 文件

.NOTPARALLEL: \$(PX4_ROOT)/Archives/px4fmu-v1.export \$(PX4_ROOT)/Archives/px4fmu-v2.export \$(PX4_ROOT)/Archives/px4fmu-v4.export \$(PX4_ROOT)/Archives/px4io-v1.export \$(PX4_ROOT)/Archives/px4io-v2.export

NOTPARALLEL新语法：Makefile中，如果出现目标“.NOPARALLEL”，则所有命令按照串行方式执行，即使存在make的命令行参数“-j”。但在递归调用的字make进程中，命令可以并行执行。此目标不应该有依赖文件，所有出现的依赖文件将被忽略。

px4_targets.mk

px4_common.mk添加驱动、系统命令等模块

firmware.mk  注释：GenericMakefile for PX4 firmware images. 通用MakefilePX4固件镜像。

include $(MK_DIR)/setup.mk     /c/ardupilot/modules/PX4Firmware/makefiles/setup.mk目的是Get path and tool config 即设置路径和toolinclude $(PX4_MK_DIR)/$(PX4_TARGET_OS).mk  /c/ardupilot/modules/PX4Firmware/makefiles/nuttx.mk目的是Rules and definitions related to handling the NuttX export archives when building firmware.即Nuttx输出的相关规则和定义# Make a list of the object files we expect to build from modules# Note that this path will typically contain a double-slash at the WORK_DIR boundary; this must be# preserved as it is used below to get the absolute path for the module.mk file correct.#MODULE_OBJS:= $(foreach path,$(dir $(MODULE_MKFILES)),$(WORK_DIR)$(path)module.pre.o)# rules to build module objects.PHONY: $(MODULE_OBJS)$(MODULE_OBJS):relpath = $(patsubst $(WORK_DIR)%,%,$@)$(MODULE_OBJS):mkfile = $(patsubst %module.pre.o,%module.mk,$(relpath))$(MODULE_OBJS):workdir = $(@D)$(MODULE_OBJS):$(GLOBAL_DEPS) $(NUTTX_CONFIG_HEADER)$(Q) $(MKDIR) -p $(workdir)$(Q)+ $(MAKE) -r -f $(PX4_MK_DIR)module.mk \-C $(workdir) \MODULE_WORK_DIR=$(workdir) \MODULE_OBJ=$@ \MODULE_MK=$(mkfile) \MODULE_NAME=$(lastword $(subst /, ,$(workdir))) \Module

这段是module的obj文件生成规则，规定了module的路径、makefile文件路径、工作目录等，并生成obj文件

# make a list of phony clean targets for modulesMODULE_CLEANS:= $(foreach path,$(dir $(MODULE_MKFILES)),$(WORK_DIR)$(path)/clean)# rules to clean modules.PHONY: $(MODULE_CLEANS)$(MODULE_CLEANS):relpath = $(patsubst $(WORK_DIR)%,%,$@)$(MODULE_CLEANS):mkfile = $(patsubst %clean,%module.mk,$(relpath))$(MODULE_CLEANS):@$(ECHO) %% cleaning using $(mkfile)$(Q)+ $(MAKE) -r -f $(PX4_MK_DIR)module.mk \MODULE_WORK_DIR=$(dir $@) \MODULE_MK=$(mkfile) \Clean

这段是clean module的规则，清除的路径、makefile的路径。

# Make a list of the archive files we expect to build from libraries# Note that this path will typically contain a double-slash at the WORK_DIR boundary; this must be# preserved as it is used below to get the absolute path for the library.mk file correct.#LIBRARY_LIBS:= $(foreach path,$(dir $(LIBRARY_MKFILES)),$(WORK_DIR)$(path)library.a)# rules to build module objects.PHONY: $(LIBRARY_LIBS)$(LIBRARY_LIBS):relpath = $(patsubst $(WORK_DIR)%,%,$@)$(LIBRARY_LIBS):mkfile = $(patsubst %library.a,%library.mk,$(relpath))$(LIBRARY_LIBS):workdir = $(@D)$(LIBRARY_LIBS):$(GLOBAL_DEPS) $(NUTTX_CONFIG_HEADER)$(Q) $(MKDIR) -p $(workdir)$(Q)+ $(MAKE) -r -f $(PX4_MK_DIR)library.mk \-C $(workdir) \LIBRARY_WORK_DIR=$(workdir) \LIBRARY_LIB=$@ \LIBRARY_MK=$(mkfile) \LIBRARY_NAME=$(lastword $(subst /, ,$(workdir))) \Library

这段是库的obj文件生成规则，规定了库的路径、makefile文件路径、工作目录等，并生成obj文件

# make a list of phony clean targets for modulesLIBRARY_CLEANS:= $(foreach path,$(dir $(LIBRARY_MKFILES)),$(WORK_DIR)$(path)/clean)# rules to clean modules.PHONY: $(LIBRARY_CLEANS)$(LIBRARY_CLEANS):relpath = $(patsubst $(WORK_DIR)%,%,$@)$(LIBRARY_CLEANS):mkfile = $(patsubst %clean,%library.mk,$(relpath))$(LIBRARY_CLEANS):@$(ECHO) %% cleaning using $(mkfile)$(Q)+ $(MAKE) -r -f $(PX4_MK_DIR)library.mk \LIBRARY_WORK_DIR=$(dir $@) \LIBRARY_MK=$(mkfile) \clean

这段是clean 库的规则，清除的路径、makefile的路径。

以下是直接复制的，主要实现相关的编译功能，有相应的注释。

################################################################################# Builtin command list generation################################################################################## Builtin commands can be generated by the configuration, in which case they# must refer to commands that already exist, or indirectly generated by modules# when they are built.## The configuration supplies builtin command information in the BUILTIN_COMMANDS# variable. Applications make empty files in $(WORK_DIR)/builtin_commands whose# filename contains the same information.## In each case, the command information consists of four fields separated with a# period. These fields are the command's name, its thread priority, its stack size# and the name of the function to call when starting the thread.## BUILTIN_COMMANDS#Contains a list of built-in commands not explicitly provided#by modules / libraries. Each entry in this list is formatted#as <command>.<priority>.<stacksize>.<entrypoint>BUILTIN_CSRC = $(WORK_DIR)builtin_commands.c# command definitions from modules (may be empty at Makefile parsing time...)MODULE_COMMANDS = $(subst COMMAND.,,$(notdir $(wildcard $(WORK_DIR)builtin_commands/COMMAND.*)))# We must have at least one pre-defined builtin command in order to generate# any of this.#ifneq ($(BUILTIN_COMMANDS),)# (BUILTIN_PROTO,<cmdspec>,<outputfile>)define BUILTIN_PROTO$(ECHO) 'extern int $(word 4,$1)(int argc, char *argv[]);' >> $2;endef# (BUILTIN_DEF,<cmdspec>,<outputfile>)define BUILTIN_DEF$(ECHO) '    {"$(word 1,$1)", $(word 2,$1), $(word 3,$1), $(word 4,$1)},' >> $2;endef# Don't generate until modules have updated their command files$(BUILTIN_CSRC):$(GLOBAL_DEPS) $(MODULE_OBJS) $(MODULE_MKFILES) $(BUILTIN_COMMAND_FILES)@$(ECHO) "CMDS:    $@"$(Q) $(ECHO) '/* builtin command list - automatically generated, do not edit */' > $@$(Q) $(ECHO) '#include <nuttx/config.h>' >> $@$(Q) $(ECHO) '#include <nuttx/binfmt/builtin.h>' >> $@$(Q) $(foreach spec,$(BUILTIN_COMMANDS),$(call BUILTIN_PROTO,$(subst ., ,$(spec)),$@))$(Q) $(foreach spec,$(MODULE_COMMANDS),$(call BUILTIN_PROTO,$(subst ., ,$(spec)),$@))$(Q) $(ECHO) 'const struct builtin_s g_builtins[] = {' >> $@$(Q) $(foreach spec,$(BUILTIN_COMMANDS),$(call BUILTIN_DEF,$(subst ., ,$(spec)),$@))$(Q) $(foreach spec,$(MODULE_COMMANDS),$(call BUILTIN_DEF,$(subst ., ,$(spec)),$@))$(Q) $(ECHO) '    {NULL, 0, 0, NULL}' >> $@$(Q) $(ECHO) '};' >> $@$(Q) $(ECHO) 'const int g_builtin_count = $(words $(BUILTIN_COMMANDS) $(MODULE_COMMANDS));' >> $@SRCS+= $(BUILTIN_CSRC)EXTRA_CLEANS+= $(BUILTIN_CSRC)endifendif################################################################################# Default SRCS generation     ################################################################################## If there are no SRCS, the build will fail; in that case, generate an empty# source file.#ifeq ($(SRCS),)EMPTY_SRC = $(WORK_DIR)empty.c$(EMPTY_SRC):$(Q) $(ECHO) '/* this is an empty file */' > $@SRCS+= $(EMPTY_SRC)endif################################################################################# Build rules################################################################################ifeq ($(PX4_TARGET_OS),nuttx)## What we're going to build.#PRODUCT_BUNDLE = $(WORK_DIR)firmware.px4PRODUCT_BIN = $(WORK_DIR)firmware.binPRODUCT_ELF = $(WORK_DIR)firmware.elfPRODUCT_PARAMXML = $(WORK_DIR)/parameters.xml.PHONY:firmwarefirmware:$(PRODUCT_BUNDLE)endif## Object files we will generate from sources#OBJS:= $(foreach src,$(SRCS),$(WORK_DIR)$(src).o)## SRCS -> OBJS rules        将源文件编译成obj文件#$(OBJS):$(GLOBAL_DEPS)$(filter %.c.o,$(OBJS)): $(WORK_DIR)%.c.o: %.c $(GLOBAL_DEPS)$(call COMPILE,$<,$@)$(filter %.cpp.o,$(OBJS)): $(WORK_DIR)%.cpp.o: %.cpp $(GLOBAL_DEPS)$(call COMPILEXX,$<,$@)$(filter %.S.o,$(OBJS)): $(WORK_DIR)%.S.o: %.S $(GLOBAL_DEPS)$(call ASSEMBLE,$<,$@)ifeq ($(PX4_TARGET_OS),nuttx)## Built product rules#$(PRODUCT_BUNDLE):$(PRODUCT_BIN)@$(ECHO) %% Generating $@ifdef GEN_PARAM_XML$(Q) $(PYTHON) $(PX4_BASE)/Tools/px_process_params.py --src-path $(PX4_BASE)/src --board CONFIG_ARCH_BOARD_$(CONFIG_BOARD) --xml$(Q) $(MKFW) --prototype $(IMAGE_DIR)/$(BOARD).prototype \--git_identity $(PX4_BASE) \--parameter_xml $(PRODUCT_PARAMXML) \--image $< > $@else$(Q) $(MKFW) --prototype $(IMAGE_DIR)/$(BOARD).prototype \--git_identity $(PX4_BASE) \--image $< > $@endif$(PRODUCT_BIN):$(PRODUCT_ELF)$(call SYM_TO_BIN,$<,$@)$(PRODUCT_ELF):$(OBJS) $(MODULE_OBJS) $(LIBRARY_LIBS) $(GLOBAL_DEPS) $(LINK_DEPS) $(MODULE_MKFILES)$(call LINK,$@,$(OBJS) $(MODULE_OBJS) $(LIBRARY_LIBS))## Utility rules         实用的规则#.PHONY: uploadupload:$(PRODUCT_BUNDLE) $(PRODUCT_BIN)$(Q) $(MAKE) -f $(PX4_MK_DIR)/upload.mk \METHOD=serial \CONFIG=$(CONFIG) \BOARD=$(BOARD) \BUNDLE=$(PRODUCT_BUNDLE) \BIN=$(PRODUCT_BIN).PHONY: cleanclean:$(MODULE_CLEANS)@$(ECHO) %% cleaning$(Q) $(REMOVE) $(PRODUCT_BUNDLE) $(PRODUCT_BIN) $(PRODUCT_ELF)$(Q) $(REMOVE) $(OBJS) $(DEP_INCLUDES) $(EXTRA_CLEANS)$(Q) $(RMDIR) $(NUTTX_EXPORT_DIR)endif# Include the OS specific build rules# The rules must define the "firmware" make target#ifeq ($(PX4_TARGET_OS),nuttx)# TODO# Move above nuttx specific rules to $(MK_DIR)/nuttx_romfs.mkendififeq ($(PX4_TARGET_OS),posix)include $(MK_DIR)/posix_elf.mkendififeq ($(PX4_TARGET_OS),qurt)include $(MK_DIR)/qurt_elf.mkendif## DEP_INCLUDES is defined by the toolchain include in terms of $(OBJS)#-include $(DEP_INCLUDES)

通过firmware.mk文件阅读，终于知道.px4是如何编译出来的了，如何添加lib、module，从而用于裁剪程序。其实.mk文件只是将ccs或者kile等软件的编译工作完成，自行设置编译规则、编译什么文件、分配芯片占用空间等等。至于具体程序的裁剪，若在.mk文件中去掉lib或者module，最后下载进板子的程序就不会有这部分内容，就没法运行；若.mk添加了，但在rcS、Rc.APM中不启动，只是占有了板子内存，并没有运行。

targets.mk，sketch_sources.mk暂时先放着