主config.mk

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我是靠谱客的博主飘逸小天鹅，最近开发中收集的这篇文章主要介绍主config.mk，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

文章目录

config.mk主要内容是编译属性和链接属性预处理属性

#
# (C) Copyright 2000-2006
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#
# See file CREDITS for list of people who contributed to this
# project.
#
# This program is free software; you can redistribute it and/or
# modify it under the terms of the GNU General Public License as
# published by the Free Software Foundation; either version 2 of
# the License, or (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston,
# MA 02111-1307 USA
#

#########################################################################

ifneq ($(OBJTREE),$(SRCTREE))			##判断是怎么编译，单独输出文件还是原地编译
ifeq ($(CURDIR),$(SRCTREE))
dir :=
else
dir := $(subst $(SRCTREE)/,,$(CURDIR))
endif

obj := $(if $(dir),$(OBJTREE)/$(dir)/,$(OBJTREE)/)
src := $(if $(dir),$(SRCTREE)/$(dir)/,$(SRCTREE)/)

$(shell mkdir -p $(obj))
else
obj :=
src :=
endif

# clean the slate ...
PLATFORM_RELFLAGS =
PLATFORM_CPPFLAGS =
PLATFORM_LDFLAGS =

#
# When cross-compiling on NetBSD, we have to define __PPC__ or else we
# will pick up a va_list declaration that is incompatible with the
# actual argument lists emitted by the compiler.
#
# [Tested on NetBSD/i386 1.5 + cross-powerpc-netbsd-1.3]

ifeq ($(ARCH),ppc)
ifeq ($(CROSS_COMPILE),powerpc-netbsd-)
PLATFORM_CPPFLAGS+= -D__PPC__
endif
ifeq ($(CROSS_COMPILE),powerpc-openbsd-)
PLATFORM_CPPFLAGS+= -D__PPC__
endif
endif

ifeq ($(ARCH),arm)
ifeq ($(CROSS_COMPILE),powerpc-netbsd-)
PLATFORM_CPPFLAGS+= -D__ARM__
endif
ifeq ($(CROSS_COMPILE),powerpc-openbsd-)
PLATFORM_CPPFLAGS+= -D__ARM__
endif
endif

#########################################################################
##都是编译链接的属性
CONFIG_SHELL	:= $(shell if [ -x "$$BASH" ]; then echo $$BASH; 
		    else if [ -x /bin/bash ]; then echo /bin/bash; 
		    else echo sh; fi ; fi)

ifeq ($(HOSTOS)-$(HOSTARCH),darwin-ppc)
HOSTCC		= cc
else
HOSTCC		= gcc
endif
HOSTCFLAGS	= -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer
HOSTSTRIP	= strip

#########################################################################
#
# Option checker (courtesy linux kernel) to ensure
# only supported compiler options are used
#
cc-option = $(shell if $(CC) $(CFLAGS) $(1) -S -o /dev/null -xc /dev/null 
		> /dev/null 2>&1; then echo "$(1)"; else echo "$(2)"; fi ;)

#
# Include the make variables (CC, etc...)
#
AS	= $(CROSS_COMPILE)as			##这里的CROSS_COMPILE就是主makefile里边存放交叉编译工具链前缀的变量
LD	= $(CROSS_COMPILE)ld
CC	= $(CROSS_COMPILE)gcc
CPP	= $(CC) -E
AR	= $(CROSS_COMPILE)ar
NM	= $(CROSS_COMPILE)nm
LDR	= $(CROSS_COMPILE)ldr
STRIP	= $(CROSS_COMPILE)strip
OBJCOPY = $(CROSS_COMPILE)objcopy
OBJDUMP = $(CROSS_COMPILE)objdump
RANLIB	= $(CROSS_COMPILE)RANLIB

#########################################################################

# Load generated board configuration
sinclude $(OBJTREE)/include/autoconf.mk		##autoconf.mk由编译过程生成的;这个文件的原料来自于include/configs/xxx.h(x210_sd.h)
##这个文件的作用是用来指导uboot编译的过程;里边都是一些宏定义（或者变量），可影响编译的走向，原因就是条件编译
ifdef	ARCH
sinclude $(TOPDIR)/$(ARCH)_config.mk	# include architecture dependend rules
endif											##TOPDIR根目录/arm_config.mk    	里边是关于预处理的;下边同理
ifdef	CPU
sinclude $(TOPDIR)/cpu/$(CPU)/config.mk	# include  CPU	specific rules
endif
ifdef	SOC
sinclude $(TOPDIR)/cpu/$(CPU)/$(SOC)/config.mk	# include  SoC	specific rules
endif
ifdef	VENDOR
BOARDDIR = $(VENDOR)/$(BOARD)
else
BOARDDIR = $(BOARD)
endif
ifdef	BOARD
sinclude $(TOPDIR)/board/$(BOARDDIR)/config.mk	# include board specific rules
endif

#########################################################################

ifneq (,$(findstring s,$(MAKEFLAGS)))
ARFLAGS = cr
else
ARFLAGS = crv
endif
RELFLAGS= $(PLATFORM_RELFLAGS)
DBGFLAGS= -g # -DDEBUG
OPTFLAGS= -Os #-fomit-frame-pointer
ifndef LDSCRIPT
#LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds.debug
ifeq ($(CONFIG_NAND_U_BOOT),y)    	##如果在autoconf.mk定义了CONFIG_NAND_U_BOOT
LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot-nand.lds
else
LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds	##这 里指定了链接脚本
endif
endif
OBJCFLAGS += --gap-fill=0xff

gccincdir := $(shell $(CC) -print-file-name=include)

CPPFLAGS := $(DBGFLAGS) $(OPTFLAGS) $(RELFLAGS)		
	-D__KERNEL__
ifneq ($(TEXT_BASE),) 			##这个TEXT_BASE在主makefile里定义的在2589行左右;创建一个文件，把TEXT_BASE的值创建并写入到指定路径
CPPFLAGS += -DTEXT_BASE=$(TEXT_BASE)
endif

ifneq ($(OBJTREE),$(SRCTREE))
CPPFLAGS += -I$(OBJTREE)/include2 -I$(OBJTREE)/include
endif

CPPFLAGS += -I$(TOPDIR)/include
CPPFLAGS += -fno-builtin -ffreestanding -nostdinc	
	-isystem $(gccincdir) -pipe $(PLATFORM_CPPFLAGS)

ifdef BUILD_TAG
CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes 
	-DBUILD_TAG='"$(BUILD_TAG)"'
else
CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes
endif

CFLAGS += $(call cc-option,-fno-stack-protector)

# avoid trigraph warnings while parsing pci.h (produced by NIOS gcc-2.9)
# this option have to be placed behind -Wall -- that's why it is here
ifeq ($(ARCH),nios)
ifeq ($(findstring 2.9,$(shell $(CC) --version)),2.9)
CFLAGS := $(CPPFLAGS) -Wall -Wno-trigraphs
endif
endif

# $(CPPFLAGS) sets -g, which causes gcc to pass a suitable -g<format>
# option to the assembler.
AFLAGS_DEBUG :=

# turn jbsr into jsr for m68k
ifeq ($(ARCH),m68k)
ifeq ($(findstring 3.4,$(shell $(CC) --version)),3.4)
AFLAGS_DEBUG := -Wa,-gstabs,-S
endif
endif

AFLAGS := $(AFLAGS_DEBUG) -D__ASSEMBLY__ $(CPPFLAGS)

LDFLAGS += -Bstatic -T $(LDSCRIPT) $(PLATFORM_LDFLAGS)
ifneq ($(TEXT_BASE),)
LDFLAGS += -Ttext $(TEXT_BASE)
endif

# Location of a usable BFD library, where we define "usable" as
# "built for ${HOST}, supports ${TARGET}".  Sensible values are
# - When cross-compiling: the root of the cross-environment
# - Linux/ppc (native): /usr
# - NetBSD/ppc (native): you lose ... (must extract these from the
#   binutils build directory, plus the native and U-Boot include
#   files don't like each other)
#
# So far, this is used only by tools/gdb/Makefile.

ifeq ($(HOSTOS)-$(HOSTARCH),darwin-ppc)
BFD_ROOT_DIR =		/usr/local/tools
else
ifeq ($(HOSTARCH),$(ARCH))
# native
BFD_ROOT_DIR =		/usr
else
#BFD_ROOT_DIR =		/LinuxPPC/CDK		# Linux/i386
#BFD_ROOT_DIR =		/usr/pkg/cross		# NetBSD/i386
BFD_ROOT_DIR =		/opt/powerpc
endif
endif

ifeq ($(PCI_CLOCK),PCI_66M)
CFLAGS := $(CFLAGS) -DPCI_66M
endif

#########################################################################

export	CONFIG_SHELL HPATH HOSTCC HOSTCFLAGS CROSS_COMPILE 
	AS LD CC CPP AR NM STRIP OBJCOPY OBJDUMP 
	MAKE
export	TEXT_BASE PLATFORM_CPPFLAGS PLATFORM_RELFLAGS CPPFLAGS CFLAGS AFLAGS

#########################################################################

ifndef REMOTE_BUILD

%.s:	%.S
	$(CPP) $(AFLAGS) -o $@ $<
%.o:	%.S
	$(CC) $(AFLAGS) -c -o $@ $<
%.o:	%.c
	$(CC) $(CFLAGS) -c -o $@ $<

else

$(obj)%.s:	%.S
	$(CPP) $(AFLAGS) -o $@ $<
$(obj)%.o:	%.S
	$(CC) $(AFLAGS) -c -o $@ $<
$(obj)%.o:	%.c
	$(CC) $(CFLAGS) -c -o $@ $<
endif

#########################################################################