#
# (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))
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 $(obj))
else
obj :=
src :=
endif
# clean the slate ...
PLATFORM_RELFLAGS =
PLATFORM_CPPFLAGS =
PLATFORM_LDFLAGS =
#########################################################################
ifeq ($(HOSTOS),darwin)
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
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
ifdef ARCH
sinclude $(TOPDIR)/lib_$(ARCH)/config.mk # include architecture dependend rules
endif
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)
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=$(TEXT_BASE)
endif
ifneq ($(RESET_VECTOR_ADDRESS),)
CPPFLAGS += -DRESET_VECTOR_ADDRESS=$(RESET_VECTOR_ADDRESS)
endif
ifneq ($(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
# $(CPPFLAGS) sets -g, which causes gcc to pass a suitable -g
# option to the assembler.
AFLAGS_DEBUG :=
# turn jbsr into jsr for m68k
ifeq ($(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 $(obj)u-boot.lds $(PLATFORM_LDFLAGS)
ifneq ($(TEXT_BASE),)
LDFLAGS += -Ttext $(TEXT_BASE)
endif
#定义AR选项ARFLAGS，调试选项DBGFLAGS，优化选项OPTFLAGS
#预处理选项CPPFLAGS，C编译器选项CFLAGS，连接选项LDFLAGS #LDFLAGS += -Bstatic -T $(LDSCRIPT) -Ttext $(TEXT_BASE) #$(PLATFORM_LDFLAGS) #指定了起始地址TEXT_BASE
关于连接的具体细节可以去查看：
http://blog.chinaunix.net/u3/114831/showart_2241591.html # 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),darwin)
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
#########################################################################
export HOSTCC HOSTCFLAGS CROSS_COMPILE \
AS LD CC CPP AR NM STRIP OBJCOPY OBJDUMP MAKE
export TEXT_BASE PLATFORM_CPPFLAGS PLATFORM_RELFLAGS CPPFLAGS CFLAGS AFLAGS
#########################################################################
# Allow boards to use custom optimize flags on a per dir/file basis
BCURDIR := $(notdir $(CURDIR))
$(obj)%.s: %.S
$(CPP) $(AFLAGS) $(AFLAGS_$(@F)) $(AFLAGS_$(BCURDIR)) -o $@ $<
$(obj)%.o: %.S
$(CC) $(AFLAGS) $(AFLAGS_$(@F)) $(AFLAGS_$(BCURDIR)) -o $@ $< -c
$(obj)%.o: %.c
$(CC) $(CFLAGS) $(CFLAGS_$(@F)) $(CFLAGS_$(BCURDIR)) -o $@ $< -c
$(obj)%.i: %.c
$(CPP) $(CFLAGS) $(CFLAGS_$(@F)) $(CFLAGS_$(BCURDIR)) -o $@ $< -c
$(obj)%.s: %.c
$(CC) $(CFLAGS) $(CFLAGS_$(@F)) $(CFLAGS_$(BCURDIR)) -o $@ $< -c -S
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