Exynos4412 Uboot学习 （一）—— Uboot 编译流程分析

 

一、执行build_uboot.sh脚本

1、./build_uboot.sh POP_1GDDR
1.1、

make itop_4412_android_config_pop_1GDDR （ 进入Makefile 执行）
itop_4412_android_config_pop_1GDDR:		unconfig
$(MKCONFIG) $(@:_config=) arm arm_cortexa9 smdkc210 samsung s5pc210 POP_1GDDR
(/home/hjx/work/itop-4412/iTop4412_uboot/mkconfig itop_4412_android_config_pop_1GDDR arm arm_cortexa9 smdkc210 samsung s5pc210 POP_1GDDR)

 1.1.1、mkconfig执行

     a、完成创建incline/config.mk

ARCH   = arm
CPU    = arm_cortexa9
BOARD  = smdkc210
VENDOR = samsung
SOC    = s5pc210
CORE   =  POP

     b、创建include/config.h

#define CONFIG_POP_1GDDR
#define CONFIG_BOARDDIR board/samsung/smdkc210
#include <config_defaults.h>
#include <configs/itop_4412_android.h>
#include <asm/config.h>

1.2、make -j$CPU_JOB_NUM （make -j$1）
1.2.1 创建include/autoconf.mk.dep

$(obj)include/autoconf.mk.dep: $(obj)include/config.h include/common.h
@$(XECHO) Generating $@ ; \
set -e ; \
: Generate the dependancies ; \
$(CC) -x c -DDO_DEPS_ONLY -M $(HOSTCFLAGS) $(CPPFLAGS) \
-MQ $(obj)include/autoconf.mk include/common.h > $@

1.2.2 创建 include/autoconf.mk.dep

$(obj)include/autoconf.mk.dep: $(obj)include/config.h include/common.h
@$(XECHO) Generating $@ ; \
set -e ; \
: Generate the dependancies ; \
$(CC) -x c -DDO_DEPS_ONLY -M $(HOSTCFLAGS) $(CPPFLAGS) \
-MQ $(obj)include/autoconf.mk include/common.h > $@

1.2.3 make all
 all: $(ALL)
 执行u-boot.srec u-boot.bin System.map 

ALL += $(obj)u-boot.srec $(obj)u-boot.bin $(obj)System.map

a、--------------------------------------------------------------------
$(obj)u-boot.srec:	$(obj)u-boot
$(OBJCOPY) -O srec $< $@
(/usr/local/arm/arm-2009q3/bin/arm-none-linux-gnueabi-objcopy -O srec u-boot u-boot.srec')
b、--------------------------------------------------------------------
$(obj)u-boot.bin:	$(obj)u-boot
$(OBJCOPY) ${OBJCFLAGS} -O binary $< $@
(/usr/local/arm/arm-2009q3/bin/arm-none-linux-gnueabi-objcopy --gap-fill=0xff -O binary u-boot u-boot.bin)

@split -b 14336 u-boot.bin bl2
@+make -C sdfuse_q/
@./sdfuse_q/chksum
@./sdfuse_q/add_padding
@rm bl2a*
(
./sdfuse_q/chksum  执行结果生成checksum_bl2_14k.bin
bl2aa file size= 14336B
./sdfuse_q/add_padding
before padding uboot.bin file size= 249988B
85884 B written
rm bl2a*
)

GEN_UBOOT = \
UNDEF_SYM=`$(OBJDUMP) -x $(LIBBOARD) $(LIBS) | \
sed  -n -e 's/.*\($(SYM_PREFIX)__u_boot_cmd_.*\)/-u\1/p'|sort|uniq`;\
cd $(LNDIR) && $(LD) $(LDFLAGS) $$UNDEF_SYM $(__OBJS) \
--start-group $(__LIBS) --end-group $(PLATFORM_LIBS) \
-Map u-boot.map -o u-boot

c、--------------------------------------------------------------------
$(obj)u-boot:	depend $(SUBDIRS) $(OBJS) $(LIBBOARD) $(LIBS) $(LDSCRIPT) $(obj)u-boot.lds
$(GEN_UBOOT)

d、--------------------------------------------------------------------
depend dep:	$(TIMESTAMP_FILE) $(VERSION_FILE) $(obj)include/autoconf.mk
for dir in $(SUBDIRS) cpu/$(CPU) $(dir $(LDSCRIPT)) ; do \
$(MAKE) -C $$dir _depend ; done

e、--------------------------------------------------------------------
$(OBJS):	depend
$(MAKE) -C cpu/$(CPU) $(if $(REMOTE_BUILD),$@,$(notdir $@))
(make -C cpu/arm_cortexa9 start.o)

f、--------------------------------------------------------------------
$(LIBS):	depend $(SUBDIRS)
$(MAKE) -C $(dir $(subst $(obj),,$@))

编译这些目录生成静态库

lib_generic/lzma/liblzma.a   lib_generic/lzo/liblzo.a
cpu/arm_cortexa9/libarm_cortexa9.a  cpu/arm_cortexa9/s5pc210/libs5pc210.a
lib_arm/libarm.a fs/cramfs/libcramfs.a
fs/fat/libfat.a fs/fdos/libfdos.a  fs/jffs2/libjffs2.a fs/reiserfs/libreiserfs.a fs/ext2/libext2fs.a  fs/yaffs2/libyaffs2.a fs/ubifs/libubifs.a
net/libnet.a
disk/libdisk.a
drivers/bios_emulator/libatibiosemu.a drivers/block/libblock.a drivers/dma/libdma.a drivers/fpga/libfpga.a
drivers/gpio/libgpio.a  drivers/hwmon/libhwmon.a  drivers/i2c/libi2c.a  drivers/input/libinput.a drivers/misc/libmisc.a
drivers/mmc/libmmc.a drivers/mtd/libmtd.a drivers/mtd/nand/libnand.a drivers/mtd/onenand/libonenand.a
drivers/mtd/ubi/libubi.a  drivers/mtd/spi/libspi_flash.a drivers/net/libnet.a  drivers/net/phy/libphy.a drivers/pci/libpci.a
drivers/pcmcia/libpcmcia.a  drivers/power/libpower.a drivers/spi/libspi.a drivers/rtc/librtc.a  drivers/serial/libserial.a
drivers/twserial/libtws.a  drivers/usb/gadget/libusb_gadget.a drivers/usb/host/libusb_host.a drivers/usb/musb/libusb_musb.a
drivers/usb/phy/libusb_phy.a  drivers/video/libvideo.a drivers/watchdog/libwatchdog.a
common/libcommon.a
libfdt/libfdt.a
api/libapi.a
post/libpost.a
board/samsung/smdkc210/libsmdkc210.a

g、--------------------------------------------------------------------
$(LIBBOARD):	depend $(LIBS)
$(MAKE) -C $(dir $(subst $(obj),,$@))

(make -C board/samsung/smdkc210/)

h、--------------------------------------------------------------------
$(LDSCRIPT):	depend
$(MAKE) -C $(dir $@) $(notdir $@)

(make -C /home/hjx/work/itop-4412/iTop4412_uboot/cpu/arm_cortexa9/ u-boot.lds)

i、--------------------------------------------------------------------
$(obj)u-boot.lds: $(LDSCRIPT)  (
$(CPP) $(CPPFLAGS) $(LDPPFLAGS) -ansi -D__ASSEMBLY__ -P - <$^ >$@

LDSCRIPT=/home/hjx/work/itop-4412/iTop4412_uboot/cpu/arm_cortexa9/u-boot.lds
CPPFLAGS=-g  -Os   -fno-common -ffixed-r8 -msoft-float   -D__KERNEL__
-DTEXT_BASE=0xc3e00000 -I/home/hjx/work/itop-4412/iTop4412_uboot/include
-fno-builtin -ffreestanding -nostdinc -isystem /usr/local/arm/arm-2009q3/bin/../lib/gcc/arm-none-linux-gnueabi/4.4.1/include
-pipe  -DCONFIG_ARM -D__ARM__ -marm  -mabi=aapcs-linux -mno-thumb-interwork -march=armv7-a
LDPPFLAGS=-include /home/hjx/work/itop-4412/iTop4412_uboot/include/u-boot/u-boot.lds.h

/usr/local/arm/arm-2009q3/bin/arm-none-linux-gnueabi-gcc -E $(CPPFLAGS) $(LDPPFLAGS)
-ansi -D__ASSEMBLY__ -P - </home/hjx/work/itop-4412/iTop4412_uboot/cpu/arm_cortexa9/u-boot.lds >u-boot.lds

1.2.4 拷贝

cp -rf checksum_bl2_14k.bin ../CodeSign4SecureBoot_POP/
cp -rf u-boot.bin ../CodeSign4SecureBoot_POP/
rm checksum_bl2_14k.bin

1.2.5 生成 u-boot-iTOP-4412.bin

cat E4412.S.BL1.SSCR.EVT1.1.bin
E4412.BL2.TZ.SSCR.EVT1.1.bin
all00_padding.bin
u-boot.bin
E4412.TZ.SSCR.EVT1.1.bin > u-boot-iTOP-4412.bin

1.2.6 生成的bin移动到iTop4412_uboot目录下

mv u-boot-iTOP-4412.bin $ ./iTop4412_uboot/
rm checksum_bl2_14k.bin
rm u-boot.bin

二、

      U-Boot 还没有类似Linux一样的可视化配置界面（比如使用 make menuconfig 来配置），要手动修改配置文件 inlucde/config/<board_name>.h 来裁剪、设置U-Boot.

配置文件中有以下两类宏。
1) 一类是选项（Options）,前缀为“CONFIG”，它们用于选择CPU、SOC、开发板类型，设置系统时钟、选择设备驱动等。

2）另一类是参数（Setting）,前缀为“CFG_”，它们用于设置malloc缓冲池的大小、U-Boot 下载文件时的默认加载地址、Flash的起始地址等。

三、总结 编译流程：

a -- 首先编译 cpu /$(CPU)/start.S，对于不同的CPU，还可能编译 cpu/$(CPU)下的其他文件；

b -- 然后，对于平台/开发板相关的每个目录、每个通用目录都使用它们个字的Makefile生成相应的库；

c -- 将a、b 步骤生成的.o .a文件按照 board / $(BOARDDIR)/config.mk文件中指定的代码段起始地址、board/$(BOARDDIR)/config.mk文件中指定的代码段起始地址、board/$(BOARDDIR）/U-Boot.lds链接脚本进行链接。

d -- 第c步得到的是ELF格式的U-Boot，后面的Makefile还会将它转换成二进制格式、S-Record格式。