yuzhongzhen 发表于 2018-3-30 10:13:10

TQ210——S5PV210 uboot顶层config.mk分析

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[*]#
[*]# (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
[*]#
[*]#########################################################################
[*]# $@表示目标文件
[*]# $^表示所有的依赖文件
[*]# $<表示第一个依赖文件
[*]# $?表示比目标还要新的依赖文件列表
[*]#########################################################################
[*]# config.mk功能是配置单板信息和编译环境,被Makefile调用
[*]
[*]
[*]#########################################################################
[*]# 此脚本在uboot顶层目录。如果目标存放目录不等于源码目录(这里不会执行)
[*]ifneq ($(OBJTREE),$(SRCTREE))
[*]ifeq ($(CURDIR),$(SRCTREE))
[*]dir :=
[*]else
[*]dir := $(subst $(SRCTREE)/,,$(CURDIR))
[*]endif
[*]
[*]
[*]obj := $(if $(dir),$(OBJTREE)/$(dir)/,$(OBJTREE)/)
[*]src := $(if $(dir),$(SRCTREE)/$(dir)/,$(SRCTREE)/)
[*]
[*]
[*]$(shell mkdir -p $(obj))
[*]# 所以上面的几行都不会执行,会执行下面这个,obj和src为空
[*]else
[*]obj :=
[*]src :=
[*]endif
[*]
[*]
[*]# clean the slate ...
[*]# 清楚标志
[*]PLATFORM_RELFLAGS =
[*]PLATFORM_CPPFLAGS =
[*]PLATFORM_LDFLAGS =
[*]
[*]
[*]#
[*]# When cross-compiling on NetBSD, we have to define __PPC__ or else we
[*]# will pick up a va_list declaration that is incompatible with the
[*]# actual argument lists emitted by the compiler.
[*]#
[*]#
[*]# ARCH=arm,这段不会执行
[*]ifeq ($(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
[*]
[*]
[*]#########################################################################
[*]
[*]
[*]CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
[*]   else if [ -x /bin/bash ]; then echo /bin/bash; \
[*]   else echo sh; fi ; fi)
[*]# 除了darwin-pcc外其他都采用gcc编译器
[*]ifeq ($(HOSTOS)-$(HOSTARCH),darwin-ppc)
[*]HOSTCC = cc
[*]else
[*]HOSTCC = gcc
[*]endif
[*]#########################################################################   
[*]# HOSTCPPFLAGS的值为空,HOSTCFLAGS = -Wall -Wstrict-prototypes -O2   
[*]# -fomit-frame-pointer   
[*]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用于检查编译器CC是否支持某选项。将2个选项作为参数传递给cc-option函数,
[*]# 该函数调用CC编译器检查参数1是否支持,若支持则函数返回参数1,
[*]# 否则返回参数2 (因此CC编译器必须支# 持参数1或参数2,若两个都不支持则会编译出错)
[*]# 可以像下面这样调用cc-option函数,并将支持的选项添加到FLAGS中:   
[*]# FLAGS +=$(call cc-option,option1,option2)   
[*]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...)
[*]# 下面一些是定义交叉工具链的集合
[*]AS = $(CROSS_COMPILE)as
[*]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
[*]
[*]
[*]#########################################################################
[*]# 加载产生的单板配置文件autoconf.mk和config.mk,均在include目录下   
[*]# config.mk中内容是ARCH CPU BOARD VENDOR SOC5个变量信息   
[*]# autoconf.mk为单板配置宏的集合,打开/关闭 用 y/n表示   
[*]# Load generated board configuration
[*]sinclude $(OBJTREE)/include/autoconf.mk
[*]
[*]
[*]ifdef ARCH
[*]sinclude $(TOPDIR)/$(ARCH)_config.mk # include architecture dependend rules
[*]endif
[*]ifdef CPU
[*]sinclude $(TOPDIR)/cpu/$(CPU)/config.mk # includeCPUspecific rules
[*]endif
[*]ifdef SOC
[*]sinclude $(TOPDIR)/cpu/$(CPU)/$(SOC)/config.mk # includeSoC 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)
[*]LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot-nand.lds
[*]else
[*]LDSCRIPT := $(TOPDIR)/board/$(BOARDDIR)/u-boot.lds
[*]endif
[*]endif
[*]OBJCFLAGS += --gap-fill=0xff
[*]
[*]
[*]gccincdir := $(shell $(CC) -print-file-name=include)
[*]
[*]
[*]CPPFLAGS := $(DBGFLAGS) $(OPTFLAGS) $(RELFLAGS) \
[*]-D__KERNEL__
[*]ifneq ($(TEXT_BASE),)
[*]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)
[*]
[*]
[*]# 没有定义BUILD_TAG,执行else分支,赋值CFLAGS   
[*]ifdef BUILD_TAG
[*]CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes \
[*]-DBUILD_TAG='"$(BUILD_TAG)"'
[*]else
[*]CFLAGS := $(CPPFLAGS) -Wall -Wstrict-prototypes
[*]endif
[*]
[*]
[*]CFLAGS += $(call cc-option,-fno-stack-protector)
[*]
[*]
[*]# avoid trigraph warnings while parsing pci.h (produced by NIOS gcc-2.9)
[*]# this option have to be placed behind -Wall -- that's why it is here
[*]# 不执行
[*]ifeq ($(ARCH),nios)
[*]ifeq ($(findstring 2.9,$(shell $(CC) --version)),2.9)
[*]CFLAGS := $(CPPFLAGS) -Wall -Wno-trigraphs
[*]endif
[*]endif
[*]
[*]
[*]# $(CPPFLAGS) sets -g, which causes gcc to pass a suitable -g<format>
[*]# option to the assembler.
[*]# CPPFLAGS设置了-g参数
[*]AFLAGS_DEBUG :=
[*]
[*]
[*]# turn jbsr into jsr for m68k
[*]ifeq ($(ARCH),m68k)
[*]ifeq ($(findstring 3.4,$(shell $(CC) --version)),3.4)
[*]AFLAGS_DEBUG := -Wa,-gstabs,-S
[*]endif
[*]endif
[*]
[*]
[*]AFLAGS := $(AFLAGS_DEBUG) -D__ASSEMBLY__ $(CPPFLAGS)
[*]
[*]
[*]# 设置uboot的链接选项
[*]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 ${TARGET}".Sensible values are
[*]# - When cross-compiling: the root of the cross-environment
[*]# - Linux/ppc (native): /usr
[*]# - NetBSD/ppc (native): you lose ... (must extract these from the
[*]#   binutils build directory, plus the native and U-Boot include
[*]#   files don't like each other)
[*]#
[*]# So far, this is used only by tools/gdb/Makefile.
[*]# 不是arm架构,不执行
[*]ifeq ($(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 := $(CFLAGS) -DPCI_66M
[*]endif
[*]
[*]
[*]#########################################################################
[*]# 输出这些信息为环境变量
[*]export CONFIG_SHELL HPATH HOSTCC HOSTCFLAGS CROSS_COMPILE \
[*]AS LD CC CPP AR NM STRIP OBJCOPY OBJDUMP \
[*]MAKE
[*]export TEXT_BASE PLATFORM_CPPFLAGS PLATFORM_RELFLAGS CPPFLAGS CFLAGS AFLAGS
[*]
[*]
[*]#########################################################################
[*]# 指定隐含的编译规则,例如:根据以上的定义,以“.s”结尾的目标文件将根据第一条规则由同名但后   
[*]# 缀为“.S”的源文件来生成,若不存在“.S”结尾的同名文件则根据最后一条规则由同名的“.c”文件生   
[*]# 成。   
[*]ifndef REMOTE_BUILD
[*]
[*]
[*]%.s: %.S
[*]$(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
[*]
[*]
[*]#########################################################################
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