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Mini2440之uboot移植之源码分析start.S(一)

在前面的文章我们已经介绍了如何自己去实现一个BootLoader,今天我们来介绍u-boot的移植,u-boot是一种通用的BootLoader。

嵌入式Linux之uboot源码make配置编译正向分析中我们已经介绍了如何通过Source Insight打开u-boot源码,以及uboot的编译过程。这一节我们将对u-boot源码进行分析,并且将uboot移植到Mini2440开发板。

在移植之前,我们首先需要明确Mini2440开发板具有的硬件资源:

  • SoC:S3C2440;
  • NAND:K9F2G08U0C;
  • 网卡:DM9000A;
  • SDRAM:HY57V561620FTP;

从网站上下载得到u-boot源码包,例如:u-boot-2016.05.tar.bz2 (最新的u-boot版本已经不支持s3c2440)。

一、uboot编译

在之前的文章中我们介绍过smdk2410的编译过程,这里再啰嗦一遍,uboot的编译分为两步:配置、编译:

1.1 配置

配置选择所要使用的board ,我调试使用的是S3C2440,但是./configs目录下没有smdk2440_defconfig这个文件,只有smdk2410_defconfig,因此执行如下命令,生成.config文件:

make smdk2410_defconfig

.config文件定义如下:

#
# Automatically generated file; DO NOT EDIT.
# U-Boot 2016.05 Configuration
#
CONFIG_CREATE_ARCH_SYMLINK=y
CONFIG_HAVE_GENERIC_BOARD=y
CONFIG_SYS_GENERIC_BOARD=y
# CONFIG_ARC is not set
CONFIG_ARM=y
# CONFIG_AVR32 is not set
# CONFIG_BLACKFIN is not set
# CONFIG_M68K is not set
# CONFIG_MICROBLAZE is not set
# CONFIG_MIPS is not set
# CONFIG_NDS32 is not set
# CONFIG_NIOS2 is not set
# CONFIG_OPENRISC is not set
# CONFIG_PPC is not set
# CONFIG_SANDBOX is not set
# CONFIG_SH is not set
# CONFIG_SPARC is not set
# CONFIG_X86 is not set
CONFIG_SYS_ARCH="arm"
CONFIG_SYS_CPU="arm920t"
CONFIG_SYS_SOC="s3c24x0"
CONFIG_SYS_VENDOR="samsung"
CONFIG_SYS_BOARD="smdk2410"
CONFIG_SYS_CONFIG_NAME="smdk2410"

#
# ARM architecture
#
CONFIG_CPU_ARM920T=y
# CONFIG_SEMIHOSTING is not set
# CONFIG_SYS_L2CACHE_OFF is not set
# CONFIG_ARCH_AT91 is not set
# CONFIG_TARGET_EDB93XX is not set
# CONFIG_TARGET_VCMA9 is not set
CONFIG_TARGET_SMDK2410=y
# CONFIG_TARGET_ASPENITE is not set
# CONFIG_TARGET_GPLUGD is not set
# CONFIG_ARCH_DAVINCI is not set
# CONFIG_KIRKWOOD is not set
# CONFIG_ARCH_MVEBU is not set
# CONFIG_TARGET_DEVKIT3250 is not set
# CONFIG_TARGET_WORK_92105 is not set
# CONFIG_TARGET_MX25PDK is not set
# CONFIG_TARGET_ZMX25 is not set
# CONFIG_TARGET_APF27 is not set
# CONFIG_TARGET_APX4DEVKIT is not set
# CONFIG_TARGET_XFI3 is not set
# CONFIG_TARGET_M28EVK is not set
# CONFIG_TARGET_MX23EVK is not set
# CONFIG_TARGET_MX28EVK is not set
# CONFIG_TARGET_MX23_OLINUXINO is not set
# CONFIG_TARGET_BG0900 is not set
# CONFIG_TARGET_SANSA_FUZE_PLUS is not set
# CONFIG_TARGET_SC_SPS_1 is not set
# CONFIG_ORION5X is not set
# CONFIG_TARGET_SPEAR300 is not set
# CONFIG_TARGET_SPEAR310 is not set
# CONFIG_TARGET_SPEAR320 is not set
# CONFIG_TARGET_SPEAR600 is not set
# CONFIG_TARGET_STV0991 is not set
# CONFIG_TARGET_X600 is not set
# CONFIG_TARGET_IMX31_PHYCORE is not set
# CONFIG_TARGET_MX31ADS is not set
# CONFIG_TARGET_MX31PDK is not set
# CONFIG_TARGET_WOODBURN is not set
# CONFIG_TARGET_WOODBURN_SD is not set
# CONFIG_TARGET_FLEA3 is not set
# CONFIG_TARGET_MX35PDK is not set
# CONFIG_ARCH_BCM283X is not set
# CONFIG_TARGET_VEXPRESS_CA15_TC2 is not set
# CONFIG_TARGET_VEXPRESS_CA5X2 is not set
# CONFIG_TARGET_VEXPRESS_CA9X4 is not set
# CONFIG_TARGET_KWB is not set
# CONFIG_TARGET_TSERIES is not set
# CONFIG_TARGET_CM_T335 is not set
# CONFIG_TARGET_PEPPER is not set
# CONFIG_TARGET_AM335X_IGEP0033 is not set
# CONFIG_TARGET_PCM051 is not set
# CONFIG_TARGET_DRACO is not set
# CONFIG_TARGET_THUBAN is not set
# CONFIG_TARGET_RASTABAN is not set
# CONFIG_TARGET_PXM2 is not set
# CONFIG_TARGET_RUT is not set
# CONFIG_TARGET_PENGWYN is not set
# CONFIG_TARGET_AM335X_BALTOS is not set
# CONFIG_TARGET_AM335X_EVM is not set
# CONFIG_TARGET_AM335X_SL50 is not set
# CONFIG_TARGET_AM43XX_EVM is not set
# CONFIG_TARGET_BAV335X is not set
# CONFIG_TARGET_TI814X_EVM is not set
# CONFIG_TARGET_TI816X_EVM is not set
# CONFIG_TARGET_BCM28155_AP is not set
# CONFIG_TARGET_BCMCYGNUS is not set
# CONFIG_TARGET_BCMNSP is not set
# CONFIG_ARCH_EXYNOS is not set
# CONFIG_ARCH_S5PC1XX is not set
# CONFIG_ARCH_HIGHBANK is not set
# CONFIG_ARCH_INTEGRATOR is not set
# CONFIG_ARCH_KEYSTONE is not set
# CONFIG_ARCH_MX7 is not set
# CONFIG_ARCH_MX6 is not set
# CONFIG_ARCH_MX5 is not set
# CONFIG_TARGET_M53EVK is not set
# CONFIG_TARGET_MX51EVK is not set
# CONFIG_TARGET_MX53ARD is not set
# CONFIG_TARGET_MX53EVK is not set
# CONFIG_TARGET_MX53LOCO is not set
# CONFIG_TARGET_MX53SMD is not set
# CONFIG_OMAP34XX is not set
# CONFIG_OMAP44XX is not set
# CONFIG_OMAP54XX is not set
# CONFIG_RMOBILE is not set
# CONFIG_ARCH_SNAPDRAGON is not set
# CONFIG_ARCH_SOCFPGA is not set
# CONFIG_TARGET_CM_T43 is not set
# CONFIG_ARCH_SUNXI is not set
# CONFIG_TARGET_TS4800 is not set
# CONFIG_TARGET_VF610TWR is not set
# CONFIG_TARGET_COLIBRI_VF is not set
# CONFIG_TARGET_PCM052 is not set
# CONFIG_ARCH_ZYNQ is not set
# CONFIG_ARCH_ZYNQMP is not set
# CONFIG_TEGRA is not set
# CONFIG_TARGET_VEXPRESS64_AEMV8A is not set
# CONFIG_TARGET_VEXPRESS64_BASE_FVP is not set
# CONFIG_TARGET_VEXPRESS64_BASE_FVP_DRAM is not set
# CONFIG_TARGET_VEXPRESS64_JUNO is not set
# CONFIG_TARGET_LS2080A_EMU is not set
# CONFIG_TARGET_LS2080A_SIMU is not set
# CONFIG_TARGET_LS2080AQDS is not set
# CONFIG_TARGET_LS2080ARDB is not set
# CONFIG_TARGET_HIKEY is not set
# CONFIG_TARGET_LS1021AQDS is not set
# CONFIG_TARGET_LS1021ATWR is not set
# CONFIG_TARGET_LS1043AQDS is not set
# CONFIG_TARGET_LS1043ARDB is not set
# CONFIG_TARGET_H2200 is not set
# CONFIG_TARGET_ZIPITZ2 is not set
# CONFIG_TARGET_COLIBRI_PXA270 is not set
# CONFIG_ARCH_UNIPHIER is not set
# CONFIG_STM32 is not set
# CONFIG_ARCH_ROCKCHIP is not set
# CONFIG_TARGET_THUNDERX_88XX is not set
# CONFIG_SYS_MALLOC_F is not set

#
# ARM debug
#
# CONFIG_DEBUG_LL is not set

#
# General setup
#
CONFIG_LOCALVERSION=""
CONFIG_LOCALVERSION_AUTO=y
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
CONFIG_EXPERT=y
CONFIG_SYS_MALLOC_CLEAR_ON_INIT=y

#
# Boot images
#
# CONFIG_FIT is not set
CONFIG_SYS_EXTRA_OPTIONS=""

#
# Boot timing
#
# CONFIG_BOOTSTAGE is not set
CONFIG_BOOTSTAGE_USER_COUNT=20
CONFIG_BOOTSTAGE_STASH_ADDR=0
CONFIG_BOOTSTAGE_STASH_SIZE=4096
# CONFIG_CONSOLE_RECORD is not set

#
# Command line interface
#
CONFIG_CMDLINE=y
CONFIG_HUSH_PARSER=y
CONFIG_SYS_HUSH_PARSER=y
CONFIG_SYS_PROMPT="SMDK2410 # "

#
# Autoboot options
#
# CONFIG_AUTOBOOT_KEYED is not set

#
# Commands
#

#
# Info commands
#
CONFIG_CMD_BDI=y
CONFIG_CMD_CONSOLE=y
# CONFIG_CMD_CPU is not set
# CONFIG_CMD_LICENSE is not set

#
# Boot commands
#
CONFIG_CMD_BOOTD=y
CONFIG_CMD_BOOTM=y
# CONFIG_CMD_BOOTZ is not set
CONFIG_CMD_ELF=y
CONFIG_CMD_GO=y
CONFIG_CMD_RUN=y
CONFIG_CMD_IMI=y
CONFIG_CMD_IMLS=y
CONFIG_CMD_XIMG=y

#
# Environment commands
#
# CONFIG_CMD_ASKENV is not set
CONFIG_CMD_EXPORTENV=y
CONFIG_CMD_IMPORTENV=y
CONFIG_CMD_EDITENV=y
# CONFIG_CMD_GREPENV is not set
CONFIG_CMD_SAVEENV=y
CONFIG_CMD_ENV_EXISTS=y

#
# Memory commands
#
CONFIG_CMD_MEMORY=y
CONFIG_CMD_CRC32=y
# CONFIG_LOOPW is not set
# CONFIG_CMD_MEMTEST is not set
# CONFIG_CMD_MX_CYCLIC is not set
# CONFIG_CMD_MEMINFO is not set

#
# Device access commands
#
CONFIG_CMD_LOADB=y
CONFIG_CMD_LOADS=y
CONFIG_CMD_FLASH=y
# CONFIG_CMD_ARMFLASH is not set
# CONFIG_CMD_MMC is not set
# CONFIG_CMD_NAND is not set
# CONFIG_CMD_SF is not set
# CONFIG_CMD_SPI is not set
# CONFIG_CMD_I2C is not set
CONFIG_CMD_USB=y
# CONFIG_CMD_DFU is not set
# CONFIG_CMD_USB_MASS_STORAGE is not set
CONFIG_CMD_FPGA=y
# CONFIG_CMD_GPIO is not set

#
# Shell scripting commands
#
CONFIG_CMD_ECHO=y
CONFIG_CMD_ITEST=y
CONFIG_CMD_SOURCE=y
# CONFIG_CMD_SETEXPR is not set

#
# Network commands
#
CONFIG_CMD_NET=y
# CONFIG_CMD_TFTPPUT is not set
# CONFIG_CMD_TFTPSRV is not set
# CONFIG_CMD_RARP is not set
CONFIG_CMD_DHCP=y
CONFIG_CMD_NFS=y
# CONFIG_CMD_MII is not set
CONFIG_CMD_PING=y
# CONFIG_CMD_CDP is not set
# CONFIG_CMD_SNTP is not set
# CONFIG_CMD_DNS is not set
# CONFIG_CMD_LINK_LOCAL is not set

#
# Misc commands
#
CONFIG_CMD_CACHE=y
# CONFIG_CMD_TIME is not set
CONFIG_CMD_MISC=y
# CONFIG_CMD_TIMER is not set

#
# Power commands
#

#
# Security commands
#

#
# Filesystem commands
#
CONFIG_CMD_EXT2=y
# CONFIG_CMD_EXT4 is not set
CONFIG_CMD_FAT=y
# CONFIG_CMD_FS_GENERIC is not set
CONFIG_SUPPORT_OF_CONTROL=y

#
# Device Tree Control
#
# CONFIG_OF_CONTROL is not set
CONFIG_NET=y
# CONFIG_NET_RANDOM_ETHADDR is not set
# CONFIG_NETCONSOLE is not set
CONFIG_NET_TFTP_VARS=y

#
# Device Drivers
#

#
# Generic Driver Options
#
# CONFIG_DM is not set
# CONFIG_ADC is not set
# CONFIG_ADC_EXYNOS is not set
# CONFIG_ADC_SANDBOX is not set
# CONFIG_BLOCK_CACHE is not set

#
# Clock
#
# CONFIG_CPU is not set

#
# Hardware crypto devices
#
# CONFIG_FSL_CAAM is not set

#
# Demo for driver model
#

#
# DFU support
#
# CONFIG_DFU_TFTP is not set

#
# DMA Support
#
# CONFIG_TI_EDMA3 is not set

#
# GPIO Support
#

#
# I2C support
#
# CONFIG_CROS_EC_KEYB is not set

#
# LED Support
#

#
# Memory Controller drivers
#

#
# Multifunction device drivers
#
# CONFIG_CROS_EC is not set
# CONFIG_FSL_SEC_MON is not set
# CONFIG_MXC_OCOTP is not set
# CONFIG_PCA9551_LED is not set
# CONFIG_WINBOND_W83627 is not set

#
# MMC Host controller Support
#

#
# MTD Support
#

#
# NAND Device Support
#
# CONFIG_NAND_DENALI is not set
# CONFIG_NAND_VF610_NFC is not set
# CONFIG_NAND_PXA3XX is not set
# CONFIG_NAND_ARASAN is not set

#
# Generic NAND options
#

#
# SPI Flash Support
#
# CONFIG_SPI_FLASH is not set
# CONFIG_PHYLIB is not set
# CONFIG_NETDEVICES is not set

#
# PCI
#

#
# Pin controllers
#

#
# Power
#

#
# Remote Processor drivers
#

#
# Real Time Clock
#

#
# Serial drivers
#
# CONFIG_DEBUG_UART is not set
# CONFIG_DEBUG_UART_SKIP_INIT is not set
# CONFIG_FSL_LPUART is not set
# CONFIG_SYS_NS16550 is not set

#
# Sound support
#
# CONFIG_SOUND is not set

#
# SPI Support
#
# CONFIG_FSL_ESPI is not set
# CONFIG_TI_QSPI is not set

#
# SPMI support
#
# CONFIG_DM_THERMAL is not set

#
# Timer Support
#

#
# TPM support
#
# CONFIG_USB is not set

#
# Graphics support
#

#
# TrueType Fonts
#
# CONFIG_VIDEO_VESA is not set
# CONFIG_VIDEO_LCD_ANX9804 is not set
# CONFIG_VIDEO_LCD_SSD2828 is not set
# CONFIG_VIDEO_MVEBU is not set
# CONFIG_PHYS_TO_BUS is not set

#
# File systems
#

#
# Library routines
#
# CONFIG_CC_OPTIMIZE_LIBS_FOR_SPEED is not set
CONFIG_HAVE_PRIVATE_LIBGCC=y
# CONFIG_USE_PRIVATE_LIBGCC is not set
CONFIG_SYS_HZ=1000
# CONFIG_USE_TINY_PRINTF is not set
CONFIG_REGEX=y
# CONFIG_LIB_RAND is not set
# CONFIG_CMD_DHRYSTONE is not set
# CONFIG_RSA is not set

#
# Hashing Support
#
# CONFIG_SHA1 is not set
# CONFIG_SHA256 is not set
# CONFIG_SHA_HW_ACCEL is not set

#
# Compression Support
#
# CONFIG_LZ4 is not set
# CONFIG_ERRNO_STR is not set
# CONFIG_OF_LIBFDT is not set
# CONFIG_SPL_OF_LIBFDT is not set
# CONFIG_UNIT_TEST is not set
View Code

这个文件和include/config/auto.conf文件内容大致差不多(auto.cfg是由.config生成的):

#
# Automatically generated file; DO NOT EDIT.
# U-Boot 2016.05 Configuration
#
CONFIG_CMD_BOOTM=y
CONFIG_CMD_USB=y
CONFIG_CMD_EDITENV=y
CONFIG_SYS_GENERIC_BOARD=y
CONFIG_CMD_CONSOLE=y
CONFIG_CMD_BOOTD=y
CONFIG_CMD_IMLS=y
CONFIG_BOOTSTAGE_STASH_ADDR=0
CONFIG_HAVE_PRIVATE_LIBGCC=y
CONFIG_CMD_BDI=y
CONFIG_ARM=y
CONFIG_CREATE_ARCH_SYMLINK=y
CONFIG_SYS_VENDOR="samsung"
CONFIG_CMD_PING=y
CONFIG_CMD_SAVEENV=y
CONFIG_CMD_MISC=y
CONFIG_SYS_CPU="arm920t"
CONFIG_BOOTSTAGE_USER_COUNT=20
CONFIG_CC_OPTIMIZE_FOR_SIZE=y
CONFIG_CMD_FLASH=y
CONFIG_REGEX=y
CONFIG_CMD_ENV_EXISTS=y
CONFIG_HAVE_GENERIC_BOARD=y
CONFIG_CMD_EXPORTENV=y
CONFIG_CMD_DHCP=y
CONFIG_SYS_EXTRA_OPTIONS=""
CONFIG_CMD_CRC32=y
CONFIG_SYS_BOARD="smdk2410"
CONFIG_SYS_CONFIG_NAME="smdk2410"
CONFIG_CMD_NFS=y
CONFIG_NET=y
CONFIG_TARGET_SMDK2410=y
CONFIG_CMD_GO=y
CONFIG_SYS_MALLOC_CLEAR_ON_INIT=y
CONFIG_CMD_IMI=y
CONFIG_SYS_HZ=1000
CONFIG_SUPPORT_OF_CONTROL=y
CONFIG_CMD_EXT2=y
CONFIG_LOCALVERSION=""
CONFIG_CMDLINE=y
CONFIG_CMD_LOADB=y
CONFIG_CMD_RUN=y
CONFIG_SYS_HUSH_PARSER=y
CONFIG_SYS_PROMPT="SMDK2410 # "
CONFIG_CMD_MEMORY=y
CONFIG_HUSH_PARSER=y
CONFIG_CMD_XIMG=y
CONFIG_CMD_ECHO=y
CONFIG_LOCALVERSION_AUTO=y
CONFIG_SYS_ARCH="arm"
CONFIG_EXPERT=y
CONFIG_SYS_SOC="s3c24x0"
CONFIG_CMD_ITEST=y
CONFIG_CMD_CACHE=y
CONFIG_BOOTSTAGE_STASH_SIZE=4096
CONFIG_CMD_LOADS=y
CONFIG_CMD_FAT=y
CONFIG_CMD_NET=y
CONFIG_CMD_FPGA=y
CONFIG_NET_TFTP_VARS=y
CONFIG_CPU_ARM920T=y
CONFIG_CMD_IMPORTENV=y
CONFIG_CMD_ELF=y
CONFIG_CMD_SOURCE=y
View Code

include/config/auto.conf是由fixdep在编译时生成的依赖文件。在顶层Makefile会引入auto.conf文件:

ifeq ($(dot-config),1)
# Read in config
-include include/config/auto.conf

这样在执行make编译过程中,就可以根据include/config/auto.conf中的宏的定义编译不同的库文件,例如common/Makefile定义:

ifndef CONFIG_SPL_BUILD
obj-y += init/
obj-y += main.o
obj-y += exports.o
obj-y += hash.o
ifdef CONFIG_SYS_HUSH_PARSER
obj-y += cli_hush.o
endif

此外,还有一个文件include/generated/autoconf.h会在执行make编译类似built-in.o目标文件时引入,这个文件是在u-boot配置生成.config文件过程中生成的,和include/config/auto.conf定义的是一样的:

/*
 *
 * Automatically generated file; DO NOT EDIT.
 * U-Boot 2016.05 Configuration
 *
 */
#define CONFIG_CMD_BOOTM 1
#define CONFIG_CMD_USB 1
#define CONFIG_CMD_EDITENV 1
#define CONFIG_SYS_GENERIC_BOARD 1
#define CONFIG_CMD_CONSOLE 1
#define CONFIG_CMD_BOOTD 1
#define CONFIG_CMD_IMLS 1
#define CONFIG_BOOTSTAGE_STASH_ADDR 0x0
#define CONFIG_HAVE_PRIVATE_LIBGCC 1
#define CONFIG_CMD_BDI 1
#define CONFIG_ARM 1
#define CONFIG_CREATE_ARCH_SYMLINK 1
#define CONFIG_SYS_VENDOR "samsung"
#define CONFIG_CMD_PING 1
#define CONFIG_CMD_SAVEENV 1
#define CONFIG_CMD_MISC 1
#define CONFIG_SYS_CPU "arm920t"
#define CONFIG_BOOTSTAGE_USER_COUNT 0x20
#define CONFIG_CC_OPTIMIZE_FOR_SIZE 1
#define CONFIG_CMD_FLASH 1
#define CONFIG_REGEX 1
#define CONFIG_CMD_ENV_EXISTS 1
#define CONFIG_HAVE_GENERIC_BOARD 1
#define CONFIG_CMD_EXPORTENV 1
#define CONFIG_CMD_DHCP 1
#define CONFIG_SYS_EXTRA_OPTIONS ""
#define CONFIG_CMD_CRC32 1
#define CONFIG_SYS_BOARD "smdk2410"
#define CONFIG_SYS_CONFIG_NAME "smdk2410"
#define CONFIG_CMD_NFS 1
#define CONFIG_NET 1
#define CONFIG_TARGET_SMDK2410 1
#define CONFIG_CMD_GO 1
#define CONFIG_SYS_MALLOC_CLEAR_ON_INIT 1
#define CONFIG_CMD_IMI 1
#define CONFIG_SYS_HZ 1000
#define CONFIG_SUPPORT_OF_CONTROL 1
#define CONFIG_CMD_EXT2 1
#define CONFIG_LOCALVERSION ""
#define CONFIG_CMDLINE 1
#define CONFIG_CMD_LOADB 1
#define CONFIG_CMD_RUN 1
#define CONFIG_SYS_HUSH_PARSER 1
#define CONFIG_SYS_PROMPT "SMDK2410 # "
#define CONFIG_CMD_MEMORY 1
#define CONFIG_HUSH_PARSER 1
#define CONFIG_CMD_XIMG 1
#define CONFIG_CMD_ECHO 1
#define CONFIG_LOCALVERSION_AUTO 1
#define CONFIG_SYS_ARCH "arm"
#define CONFIG_EXPERT 1
#define CONFIG_SYS_SOC "s3c24x0"
#define CONFIG_CMD_ITEST 1
#define CONFIG_CMD_CACHE 1
#define CONFIG_BOOTSTAGE_STASH_SIZE 0x4096
#define CONFIG_CMD_LOADS 1
#define CONFIG_CMD_FAT 1
#define CONFIG_CMD_NET 1
#define CONFIG_CMD_FPGA 1
#define CONFIG_NET_TFTP_VARS 1
#define CONFIG_CPU_ARM920T 1
#define CONFIG_CMD_IMPORTENV 1
#define CONFIG_CMD_ELF 1
#define CONFIG_CMD_SOURCE 1

总结一下include/config/auto.conf和include/generated/autoconf.h的区别,前者是定义的变量在Makefile文件中使用,后者定义的宏在代码中使用。

1.2 编译

编译、执行make命令,生成u-boot:

 make ARCH=arm CROSS_COMPILE=arm-linux-

如果需要输出u-boot反汇编代码,执行时加入-j4参数,会在u-boot根目录下生成u-boot.map文件,在map文件中,包含函数名以及函数所在文件。

 make ARCH=arm CROSS_COMPILE=arm-linux- -j4

直接反汇编u-boot文件,可以得到反汇编代码:

arm-linux-objdump -D u-boot > u-boot.dis

CROSS-COPILE是在Makefile文件中定义的变量,是用来指定交叉工具链,ARCH用来指定处理器架构。此外,我们可以在u-boot的顶层Makefile中定义:

CROSS_COMPILE=arm-linux-
ARCH=arm

这样就省去了每次编译都要在控制台输入的麻烦。

编译成功后会生成一个u-boot.bin,可以烧写到开发板上,不过一般是用不起来的,需要进一步修改。

我们在编译u-boot的时候加入V=1参数:

 make ARCH=arm CROSS_COMPILE=arm-linux- V=1

将会输出u-boot编译的完整步骤:

make -f ./Makefile silentoldconfig
make -f ./scripts/Makefile.build obj=scripts/basic
rm -f .tmp_quiet_recordmcount
make -f ./scripts/Makefile.build obj=scripts/kconfig silentoldconfig
mkdir -p include/config include/generated
scripts/kconfig/conf  --silentoldconfig Kconfig
make -f ./scripts/Makefile.autoconf || \
    { rm -f include/config/auto.conf; false; }
if [ -d arch/arm/mach-s3c24x0/include/mach ]; then    \
    dest=../../mach-s3c24x0/include/mach;            \
else                                \
    dest=arch-s3c24x0;            \
fi;                                \
ln -fsn $dest arch/arm/include/asm/arch
set -e; : '  CHK     include/config.h'; mkdir -p include/;     (echo "/* Automatically generated - do not edit */"; for i in $(echo "" | sed 's/,/ /g'); do echo \#define CONFIG_$i | sed '/=/ {s/=/    /;q; } ; { s/$/    1/; }'; done; echo \#define CONFIG_BOARDDIR board/samsung/smdk2410; echo \#include \<config_defaults.h\>; echo \#include \<config_uncmd_spl.h\>; echo \#include \<configs/"smdk2410".h\>; echo \#include \<asm/config.h\>; echo \#include \<config_fallbacks.h\>;) < scripts/Makefile.autoconf > include/config.h.tmp; if [ -r include/config.h ] && cmp -s include/config.h include/config.h.tmp; then rm -f include/config.h.tmp; else : '  UPD     include/config.h'; mv -f include/config.h.tmp include/config.h; fi
  arm-linux-gcc -E -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral   -D__KERNEL__ -D__UBOOT__   -D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux  -mword-relocations  -fno-pic  -ffunction-sections -fdata-sections -fno-common -ffixed-r9  -msoft-float   -pipe -Iinclude  -I./arch/arm/include -include ./include/linux/kconfig.h  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include  -DDO_DEPS_ONLY -dM ./include/common.h > include/autoconf.mk.tmp && { sed -n -f ./tools/scripts/define2mk.sed include/autoconf.mk.tmp | while read line; do if [ -n "" ] || ! grep -q "${line%=*}=" include/config/auto.conf; then echo "$line"; fi done > include/autoconf.mk; rm include/autoconf.mk.tmp; } || { rm include/autoconf.mk.tmp; false; }
  arm-linux-gcc -x c -DDO_DEPS_ONLY -M -MP -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral   -D__KERNEL__ -D__UBOOT__   -D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux  -mword-relocations  -fno-pic  -ffunction-sections -fdata-sections -fno-common -ffixed-r9  -msoft-float   -pipe -Iinclude  -I./arch/arm/include -include ./include/linux/kconfig.h  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -MQ include/config/auto.conf ./include/common.h > include/autoconf.mk.dep || { rm include/autoconf.mk.dep; false; }
touch include/config/auto.conf
set -e; : '  CHK     include/config/uboot.release'; mkdir -p include/config/;     echo "2016.05$(/bin/bash ./scripts/setlocalversion .)" < include/config/auto.conf > include/config/uboot.release.tmp; if [ -r include/config/uboot.release ] && cmp -s include/config/uboot.release include/config/uboot.release.tmp; then rm -f include/config/uboot.release.tmp; else : '  UPD     include/config/uboot.release'; mv -f include/config/uboot.release.tmp include/config/uboot.release; fi
set -e; : '  CHK     include/generated/version_autogenerated.h'; mkdir -p include/generated/;     (echo \#define PLAIN_VERSION \"2016.05\"; echo \#define U_BOOT_VERSION \"U-Boot \" PLAIN_VERSION; echo \#define CC_VERSION_STRING \"$(arm-linux-gcc --version | head -n 1)\"; echo \#define LD_VERSION_STRING \"$(arm-linux-ld --version | head -n 1)\"; ) < include/config/uboot.release > include/generated/version_autogenerated.h.tmp; if [ -r include/generated/version_autogenerated.h ] && cmp -s include/generated/version_autogenerated.h include/generated/version_autogenerated.h.tmp; then rm -f include/generated/version_autogenerated.h.tmp; else : '  UPD     include/generated/version_autogenerated.h'; mv -f include/generated/version_autogenerated.h.tmp include/generated/version_autogenerated.h; fi
set -e; : '  CHK     include/generated/timestamp_autogenerated.h'; mkdir -p include/generated/;     (if test -n "${SOURCE_DATE_EPOCH}"; then SOURCE_DATE="@${SOURCE_DATE_EPOCH}"; DATE=""; for date in gdate date.gnu date; do ${date} -u -d "${SOURCE_DATE}" >/dev/null 2>&1 && DATE="${date}"; done; if test -n "${DATE}"; then LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_DATE "%b %d %C%y"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_TIME "%T"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_TZ "%z"'; LC_ALL=C ${DATE} -u -d "${SOURCE_DATE}" +'#define U_BOOT_DMI_DATE "%m/%d/%Y"'; else return 42; fi; else LC_ALL=C date +'#define U_BOOT_DATE "%b %d %C%y"'; LC_ALL=C date +'#define U_BOOT_TIME "%T"'; LC_ALL=C date +'#define U_BOOT_TZ "%z"'; LC_ALL=C date +'#define U_BOOT_DMI_DATE "%m/%d/%Y"'; fi) < Makefile > include/generated/timestamp_autogenerated.h.tmp; if [ -r include/generated/timestamp_autogenerated.h ] && cmp -s include/generated/timestamp_autogenerated.h include/generated/timestamp_autogenerated.h.tmp; then rm -f include/generated/timestamp_autogenerated.h.tmp; else : '  UPD     include/generated/timestamp_autogenerated.h'; mv -f include/generated/timestamp_autogenerated.h.tmp include/generated/timestamp_autogenerated.h; fi
make -f ./scripts/Makefile.build obj=scripts/basic
rm -f .tmp_quiet_recordmcount
make -f ./scripts/Makefile.build obj=.
mkdir -p lib/
set -e; : '  CHK     include/generated/generic-asm-offsets.h'; mkdir -p include/generated/;     (set -e; echo "#ifndef __GENERIC_ASM_OFFSETS_H__"; echo "#define __GENERIC_ASM_OFFSETS_H__"; echo "/*"; echo " * DO NOT MODIFY."; echo " *"; echo " * This file was generated by Kbuild"; echo " */"; echo ""; sed -ne     "s:[[:space:]]*\.ascii[[:space:]]*\"\(.*\)\":\1:; /^->/{s:->#\(.*\):/* \1 */:; s:^->\([^ ]*\) [\$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; s:^->\([^ ]*\) [\$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"; echo ""; echo "#endif" ) < lib/asm-offsets.s > include/generated/generic-asm-offsets.h.tmp; if [ -r include/generated/generic-asm-offsets.h ] && cmp -s include/generated/generic-asm-offsets.h include/generated/generic-asm-offsets.h.tmp; then rm -f include/generated/generic-asm-offsets.h.tmp; else : '  UPD     include/generated/generic-asm-offsets.h'; mv -f include/generated/generic-asm-offsets.h.tmp include/generated/generic-asm-offsets.h; fi
mkdir -p arch/arm/lib/
set -e; : '  CHK     include/generated/asm-offsets.h'; mkdir -p include/generated/;     (set -e; echo "#ifndef __ASM_OFFSETS_H__"; echo "#define __ASM_OFFSETS_H__"; echo "/*"; echo " * DO NOT MODIFY."; echo " *"; echo " * This file was generated by Kbuild"; echo " */"; echo ""; sed -ne     "s:[[:space:]]*\.ascii[[:space:]]*\"\(.*\)\":\1:; /^->/{s:->#\(.*\):/* \1 */:; s:^->\([^ ]*\) [\$#]*\([-0-9]*\) \(.*\):#define \1 \2 /* \3 */:; s:^->\([^ ]*\) [\$#]*\([^ ]*\) \(.*\):#define \1 \2 /* \3 */:; s:->::; p;}"; echo ""; echo "#endif" ) < arch/arm/lib/asm-offsets.s > include/generated/asm-offsets.h.tmp; if [ -r include/generated/asm-offsets.h ] && cmp -s include/generated/asm-offsets.h include/generated/asm-offsets.h.tmp; then rm -f include/generated/asm-offsets.h.tmp; else : '  UPD     include/generated/asm-offsets.h'; mv -f include/generated/asm-offsets.h.tmp include/generated/asm-offsets.h; fi
make -f ./scripts/Makefile.build obj=tools
  echo "#include <../lib/crc32.c>" >tools/lib/crc32.c
  cc -Wp,-MD,tools/lib/.crc32.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE -pedantic -c -o tools/lib/crc32.o tools/lib/crc32.c
  echo "#include <../common/env_embedded.c>" >tools/common/env_embedded.c
  cc -Wp,-MD,tools/common/.env_embedded.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/common/env_embedded.o tools/common/env_embedded.c
  echo "#include <../lib/sha1.c>" >tools/lib/sha1.c
  cc -Wp,-MD,tools/lib/.sha1.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE -pedantic -c -o tools/lib/sha1.o tools/lib/sha1.c
  cc  -o tools/envcrc tools/envcrc.o tools/lib/crc32.o tools/common/env_embedded.o tools/lib/sha1.o  
  cc -Wp,-MD,tools/.gen_eth_addr.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE -pedantic -o tools/gen_eth_addr tools/gen_eth_addr.c  
  cc -Wp,-MD,tools/.img2srec.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE -pedantic -o tools/img2srec tools/img2srec.c  
  cc -Wp,-MD,tools/.mkenvimage.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/mkenvimage.o tools/mkenvimage.c
  cc  -o tools/mkenvimage tools/mkenvimage.o tools/os_support.o tools/lib/crc32.o  
  echo "#include <../common/bootm.c>" >tools/common/bootm.c
  cc -Wp,-MD,tools/common/.bootm.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/common/bootm.o tools/common/bootm.c
  echo "#include <../lib/fdtdec_common.c>" >tools/lib/fdtdec_common.c
  cc -Wp,-MD,tools/lib/.fdtdec_common.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/fdtdec_common.o tools/lib/fdtdec_common.c
  echo "#include <../lib/fdtdec.c>" >tools/lib/fdtdec.c
  cc -Wp,-MD,tools/lib/.fdtdec.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/fdtdec.o tools/lib/fdtdec.c
  cc -Wp,-MD,tools/.fit_image.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/fit_image.o tools/fit_image.c
  echo "#include <../common/image-fit.c>" >tools/common/image-fit.c
  cc -Wp,-MD,tools/common/.image-fit.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/common/image-fit.o tools/common/image-fit.c
  cc -Wp,-MD,tools/.image-host.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/image-host.o tools/image-host.c
  echo "#include <../common/image.c>" >tools/common/image.c
  cc -Wp,-MD,tools/common/.image.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/common/image.o tools/common/image.c
  echo "#include <../lib/md5.c>" >tools/lib/md5.c
  cc -Wp,-MD,tools/lib/.md5.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE -pedantic -c -o tools/lib/md5.o tools/lib/md5.c
  echo "#include <../lib/rc4.c>" >tools/lib/rc4.c
  cc -Wp,-MD,tools/lib/.rc4.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/rc4.o tools/lib/rc4.c
  echo "#include <../lib/sha256.c>" >tools/lib/sha256.c
  cc -Wp,-MD,tools/lib/.sha256.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE -pedantic -c -o tools/lib/sha256.o tools/lib/sha256.c
  echo "#include <../common/hash.c>" >tools/common/hash.c
  cc -Wp,-MD,tools/common/.hash.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/common/hash.o tools/common/hash.c
  echo "#include <../lib/libfdt/fdt.c>" >tools/lib/libfdt/fdt.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt.o tools/lib/libfdt/fdt.c
  echo "#include <../lib/libfdt/fdt_ro.c>" >tools/lib/libfdt/fdt_ro.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt_ro.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt_ro.o tools/lib/libfdt/fdt_ro.c
  echo "#include <../lib/libfdt/fdt_rw.c>" >tools/lib/libfdt/fdt_rw.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt_rw.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt_rw.o tools/lib/libfdt/fdt_rw.c
  echo "#include <../lib/libfdt/fdt_strerror.c>" >tools/lib/libfdt/fdt_strerror.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt_strerror.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt_strerror.o tools/lib/libfdt/fdt_strerror.c
  echo "#include <../lib/libfdt/fdt_wip.c>" >tools/lib/libfdt/fdt_wip.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt_wip.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt_wip.o tools/lib/libfdt/fdt_wip.c
  echo "#include <../lib/libfdt/fdt_region.c>" >tools/lib/libfdt/fdt_region.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt_region.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt_region.o tools/lib/libfdt/fdt_region.c
  echo "#include <../lib/libfdt/fdt_sw.c>" >tools/lib/libfdt/fdt_sw.c
  cc -Wp,-MD,tools/lib/libfdt/.fdt_sw.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/lib/libfdt/fdt_sw.o tools/lib/libfdt/fdt_sw.c
  cc -Wp,-MD,tools/.dumpimage.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/dumpimage.o tools/dumpimage.c
  cc  -o tools/dumpimage tools/aisimage.o tools/atmelimage.o tools/common/bootm.o tools/lib/crc32.o tools/default_image.o tools/lib/fdtdec_common.o tools/lib/fdtdec.o tools/fit_common.o tools/fit_image.o tools/gpimage.o tools/gpimage-common.o tools/common/image-fit.o tools/image-host.o tools/common/image.o tools/imagetool.o tools/imximage.o tools/kwbimage.o tools/lib/md5.o tools/lpc32xximage.o tools/mxsimage.o tools/omapimage.o tools/os_support.o tools/pblimage.o tools/pbl_crc32.o tools/lib/rc4.o tools/rkcommon.o tools/rkimage.o tools/rksd.o tools/rkspi.o tools/socfpgaimage.o tools/lib/sha1.o tools/lib/sha256.o tools/common/hash.o tools/ublimage.o tools/zynqimage.o tools/lib/libfdt/fdt.o tools/lib/libfdt/fdt_ro.o tools/lib/libfdt/fdt_rw.o tools/lib/libfdt/fdt_strerror.o tools/lib/libfdt/fdt_wip.o tools/lib/libfdt/fdt_region.o tools/lib/libfdt/fdt_sw.o tools/dumpimage.o  
  cc -Wp,-MD,tools/.mkimage.o.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -c -o tools/mkimage.o tools/mkimage.c
  cc  -o tools/mkimage tools/aisimage.o tools/atmelimage.o tools/common/bootm.o tools/lib/crc32.o tools/default_image.o tools/lib/fdtdec_common.o tools/lib/fdtdec.o tools/fit_common.o tools/fit_image.o tools/gpimage.o tools/gpimage-common.o tools/common/image-fit.o tools/image-host.o tools/common/image.o tools/imagetool.o tools/imximage.o tools/kwbimage.o tools/lib/md5.o tools/lpc32xximage.o tools/mxsimage.o tools/omapimage.o tools/os_support.o tools/pblimage.o tools/pbl_crc32.o tools/lib/rc4.o tools/rkcommon.o tools/rkimage.o tools/rksd.o tools/rkspi.o tools/socfpgaimage.o tools/lib/sha1.o tools/lib/sha256.o tools/common/hash.o tools/ublimage.o tools/zynqimage.o tools/lib/libfdt/fdt.o tools/lib/libfdt/fdt_ro.o tools/lib/libfdt/fdt_rw.o tools/lib/libfdt/fdt_strerror.o tools/lib/libfdt/fdt_wip.o tools/lib/libfdt/fdt_region.o tools/lib/libfdt/fdt_sw.o tools/mkimage.o  
  cc -Wp,-MD,tools/.proftool.d -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer   -include ./include/libfdt_env.h -idirafterinclude -idirafter./arch/arm/include -I./lib/libfdt -I./tools -DCONFIG_SYS_TEXT_BASE=0x0 -DUSE_HOSTCC -D__KERNEL_STRICT_NAMES -D_GNU_SOURCE  -o tools/proftool tools/proftool.c  
  cc  -o tools/fdtgrep tools/lib/libfdt/fdt.o tools/lib/libfdt/fdt_ro.o tools/lib/libfdt/fdt_rw.o tools/lib/libfdt/fdt_strerror.o tools/lib/libfdt/fdt_wip.o tools/lib/libfdt/fdt_region.o tools/lib/libfdt/fdt_sw.o tools/fdtgrep.o  
make -f ./scripts/Makefile.build obj=arch/arm/cpu

make -f ./scripts/Makefile.build obj=arch/arm/cpu/arm920t
make -f ./scripts/Makefile.build obj=arch/arm/cpu/arm920t/s3c24x0
arch/arm/cpu/arm920t/s3c24x0/cpu_info.o arch/arm/cpu/arm920t/s3c24x0/speed.o arch/arm/cpu/arm920t/s3c24x0/timer.o
arch/arm/cpu/arm920t/cpu.o arch/arm/cpu/arm920t/s3c24x0/built-in.o
make -f ./scripts/Makefile.build obj=arch/arm/lib

arch/arm/lib/vectors.o arch/arm/lib/crt0.o arch/arm/lib/relocate.o arch/arm/lib/bootm.o arch/arm/lib/sections.o arch/arm/lib/stack.o arch/arm/lib/interrupts.o arch/arm/lib/reset.o arch/arm/lib/cache.o arch/arm/lib/cache-cp15.o
make -f ./scripts/Makefile.build obj=board/samsung/common


make -f ./scripts/Makefile.build obj=board/samsung/smdk2410

board/samsung/smdk2410/smdk2410.o board/samsung/smdk2410/lowlevel_init.o
make -f ./scripts/Makefile.build obj=cmd
  arm-linux-gcc -Wp,-MD,cmd/.version.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(version)"  -D"KBUILD_MODNAME=KBUILD_STR(version)" -c -o cmd/version.o cmd/version.c

cmd/boot.o cmd/bootm.o cmd/help.o cmd/version.o cmd/source.o cmd/bdinfo.o cmd/cache.o cmd/console.o cmd/date.o cmd/echo.o cmd/elf.o cmd/exit.o cmd/ext2.o cmd/fat.o cmd/flash.o cmd/itest.o cmd/load.o cmd/mem.o cmd/misc.o cmd/mtdparts.o cmd/nand.o cmd/net.o cmd/pcmcia.o cmd/reginfo.o cmd/test.o cmd/ubi.o cmd/ubifs.o cmd/usb.o cmd/ximg.o cmd/yaffs2.o cmd/nvedit.o cmd/disk.o
   arm-linux-ld     -r -o cmd/built-in.o cmd/boot.o cmd/bootm.o cmd/help.o cmd/version.o cmd/source.o cmd/bdinfo.o cmd/cache.o cmd/console.o cmd/date.o cmd/echo.o cmd/elf.o cmd/exit.o cmd/ext2.o cmd/fat.o cmd/flash.o cmd/itest.o cmd/load.o cmd/mem.o cmd/misc.o cmd/mtdparts.o cmd/nand.o cmd/net.o cmd/pcmcia.o cmd/reginfo.o cmd/test.o cmd/ubi.o cmd/ubifs.o cmd/usb.o cmd/ximg.o cmd/yaffs2.o cmd/nvedit.o cmd/disk.o 
make -f ./scripts/Makefile.build obj=common
make -f ./scripts/Makefile.build obj=common/init

common/init/board_init.o
  arm-linux-gcc -Wp,-MD,common/.main.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(main)"  -D"KBUILD_MODNAME=KBUILD_STR(main)" -c -o common/main.o common/main.c
  arm-linux-gcc -Wp,-MD,common/.board_f.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(board_f)"  -D"KBUILD_MODNAME=KBUILD_STR(board_f)" -c -o common/board_f.o common/board_f.c

common/init/built-in.o common/main.o common/exports.o common/hash.o common/cli_hush.o common/autoboot.o common/bootretry.o common/board_f.o common/board_r.o common/bootm.o common/bootm_os.o common/env_attr.o common/env_callback.o common/env_flags.o common/env_flash.o common/usb.o common/usb_hub.o common/usb_storage.o common/flash.o common/splash.o common/usb_kbd.o common/env_common.o common/console.o common/dlmalloc.o common/image.o common/memsize.o common/stdio.o common/cli_simple.o common/cli.o common/cli_readline.o common/command.o common/s_record.o common/xyzModem.o

   arm-linux-ld     -r -o common/built-in.o common/init/built-in.o common/main.o common/exports.o common/hash.o common/cli_hush.o common/autoboot.o common/bootretry.o common/board_f.o common/board_r.o common/bootm.o common/bootm_os.o common/env_attr.o common/env_callback.o common/env_flags.o common/env_flash.o common/usb.o common/usb_hub.o common/usb_storage.o common/flash.o common/splash.o common/usb_kbd.o common/env_common.o common/console.o common/dlmalloc.o common/image.o common/memsize.o common/stdio.o common/cli_simple.o common/cli.o common/cli_readline.o common/command.o common/s_record.o common/xyzModem.o 
  arm-linux-gcc -Wp,-MD,common/.env_embedded.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t -Wa,--no-warn -DENV_CRC=0    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(env_embedded)"  -D"KBUILD_MODNAME=KBUILD_STR(env_embedded)" -c -o common/env_embedded.o common/env_embedded.c
make -f ./scripts/Makefile.build obj=disk

disk/part.o disk/part_dos.o
make -f ./scripts/Makefile.build obj=drivers
make -f ./scripts/Makefile.build obj=drivers/adc


make -f ./scripts/Makefile.build obj=drivers/block


make -f ./scripts/Makefile.build obj=drivers/crypto
make -f ./scripts/Makefile.build obj=drivers/crypto/fsl

drivers/crypto/fsl/sec.o
make -f ./scripts/Makefile.build obj=drivers/crypto/rsa_mod_exp



drivers/crypto/rsa_mod_exp/built-in.o drivers/crypto/fsl/built-in.o
make -f ./scripts/Makefile.build obj=drivers/dfu


make -f ./scripts/Makefile.build obj=drivers/hwmon


make -f ./scripts/Makefile.build obj=drivers/input

drivers/input/input.o
make -f ./scripts/Makefile.build obj=drivers/memory


make -f ./scripts/Makefile.build obj=drivers/misc


make -f ./scripts/Makefile.build obj=drivers/pcmcia

drivers/pcmcia/tqm8xx_pcmcia.o
make -f ./scripts/Makefile.build obj=drivers/pwm


make -f ./scripts/Makefile.build obj=drivers/rtc

drivers/rtc/date.o drivers/rtc/s3c24x0_rtc.o
make -f ./scripts/Makefile.build obj=drivers/soc


make -f ./scripts/Makefile.build obj=drivers/sound


make -f ./scripts/Makefile.build obj=drivers/spmi


make -f ./scripts/Makefile.build obj=drivers/thermal


make -f ./scripts/Makefile.build obj=drivers/timer


make -f ./scripts/Makefile.build obj=drivers/tpm


make -f ./scripts/Makefile.build obj=drivers/twserial


make -f ./scripts/Makefile.build obj=drivers/video
make -f ./scripts/Makefile.build obj=drivers/video/bridge



drivers/video/bridge/built-in.o
make -f ./scripts/Makefile.build obj=drivers/watchdog



drivers/adc/built-in.o drivers/block/built-in.o drivers/crypto/built-in.o drivers/hwmon/built-in.o drivers/misc/built-in.o drivers/pcmcia/built-in.o drivers/dfu/built-in.o drivers/rtc/built-in.o drivers/sound/built-in.o drivers/spmi/built-in.o drivers/timer/built-in.o drivers/tpm/built-in.o drivers/twserial/built-in.o drivers/video/built-in.o drivers/watchdog/built-in.o drivers/memory/built-in.o drivers/pwm/built-in.o drivers/input/built-in.o drivers/soc/built-in.o drivers/thermal/built-in.o
make -f ./scripts/Makefile.build obj=drivers/dma


make -f ./scripts/Makefile.build obj=drivers/gpio


make -f ./scripts/Makefile.build obj=drivers/i2c


make -f ./scripts/Makefile.build obj=drivers/mmc


make -f ./scripts/Makefile.build obj=drivers/mtd

drivers/mtd/mtdcore.o drivers/mtd/mtd_uboot.o drivers/mtd/mtdpart.o drivers/mtd/cfi_flash.o drivers/mtd/jedec_flash.o
make -f ./scripts/Makefile.build obj=drivers/mtd/nand

drivers/mtd/nand/nand.o drivers/mtd/nand/nand_bbt.o drivers/mtd/nand/nand_ids.o drivers/mtd/nand/nand_util.o drivers/mtd/nand/nand_ecc.o drivers/mtd/nand/nand_base.o drivers/mtd/nand/nand_timings.o drivers/mtd/nand/s3c2410_nand.o
make -f ./scripts/Makefile.build obj=drivers/mtd/onenand


make -f ./scripts/Makefile.build obj=drivers/mtd/spi


make -f ./scripts/Makefile.build obj=drivers/mtd/ubi

drivers/mtd/ubi/attach.o drivers/mtd/ubi/build.o drivers/mtd/ubi/vtbl.o drivers/mtd/ubi/vmt.o drivers/mtd/ubi/upd.o drivers/mtd/ubi/kapi.o drivers/mtd/ubi/eba.o drivers/mtd/ubi/io.o drivers/mtd/ubi/wl.o drivers/mtd/ubi/crc32.o drivers/mtd/ubi/misc.o drivers/mtd/ubi/debug.o
make -f ./scripts/Makefile.build obj=drivers/net

drivers/net/cs8900.o
make -f ./scripts/Makefile.build obj=drivers/net/phy


make -f ./scripts/Makefile.build obj=drivers/pci


make -f ./scripts/Makefile.build obj=drivers/power


make -f ./scripts/Makefile.build obj=drivers/power/battery


make -f ./scripts/Makefile.build obj=drivers/power/fuel_gauge


make -f ./scripts/Makefile.build obj=drivers/power/mfd


make -f ./scripts/Makefile.build obj=drivers/power/pmic


make -f ./scripts/Makefile.build obj=drivers/power/regulator


make -f ./scripts/Makefile.build obj=drivers/serial

drivers/serial/serial.o drivers/serial/serial_s3c24x0.o
make -f ./scripts/Makefile.build obj=drivers/spi

drivers/spi/spi.o
make -f ./scripts/Makefile.build obj=drivers/usb/common


make -f ./scripts/Makefile.build obj=drivers/usb/dwc3


make -f ./scripts/Makefile.build obj=drivers/usb/emul


make -f ./scripts/Makefile.build obj=drivers/usb/eth


make -f ./scripts/Makefile.build obj=drivers/usb/gadget


make -f ./scripts/Makefile.build obj=drivers/usb/gadget/udc


make -f ./scripts/Makefile.build obj=drivers/usb/host

drivers/usb/host/ohci-s3c24xx.o
make -f ./scripts/Makefile.build obj=drivers/usb/musb-new


make -f ./scripts/Makefile.build obj=drivers/usb/musb


make -f ./scripts/Makefile.build obj=drivers/usb/phy


make -f ./scripts/Makefile.build obj=drivers/usb/ulpi


make -f ./scripts/Makefile.build obj=fs
make -f ./scripts/Makefile.build obj=fs/ext4

fs/ext4/ext4fs.o fs/ext4/ext4_common.o fs/ext4/dev.o
make -f ./scripts/Makefile.build obj=fs/fat

fs/fat/fat.o fs/fat/file.o
make -f ./scripts/Makefile.build obj=fs/ubifs

fs/ubifs/ubifs.o fs/ubifs/io.o fs/ubifs/super.o fs/ubifs/sb.o fs/ubifs/master.o fs/ubifs/lpt.o fs/ubifs/lpt_commit.o fs/ubifs/scan.o fs/ubifs/lprops.o fs/ubifs/tnc.o fs/ubifs/tnc_misc.o fs/ubifs/debug.o fs/ubifs/crc16.o fs/ubifs/budget.o fs/ubifs/log.o fs/ubifs/orphan.o fs/ubifs/recovery.o fs/ubifs/replay.o fs/ubifs/gc.o
make -f ./scripts/Makefile.build obj=fs/yaffs2

fs/yaffs2/yaffs_allocator.o fs/yaffs2/yaffs_attribs.o fs/yaffs2/yaffs_bitmap.o fs/yaffs2/yaffs_uboot_glue.o fs/yaffs2/yaffs_checkptrw.o fs/yaffs2/yaffs_ecc.o fs/yaffs2/yaffs_error.o fs/yaffs2/yaffsfs.o fs/yaffs2/yaffs_guts.o fs/yaffs2/yaffs_nameval.o fs/yaffs2/yaffs_nand.o fs/yaffs2/yaffs_packedtags1.o fs/yaffs2/yaffs_packedtags2.o fs/yaffs2/yaffs_qsort.o fs/yaffs2/yaffs_summary.o fs/yaffs2/yaffs_tagscompat.o fs/yaffs2/yaffs_verify.o fs/yaffs2/yaffs_yaffs1.o fs/yaffs2/yaffs_yaffs2.o fs/yaffs2/yaffs_mtdif.o fs/yaffs2/yaffs_mtdif2.o

fs/fs.o fs/ext4/built-in.o fs/fat/built-in.o fs/ubifs/built-in.o fs/yaffs2/built-in.o
make -f ./scripts/Makefile.build obj=lib
make -f ./scripts/Makefile.build obj=lib/bzip2

lib/bzip2/bzlib.o lib/bzip2/bzlib_crctable.o lib/bzip2/bzlib_decompress.o lib/bzip2/bzlib_randtable.o lib/bzip2/bzlib_huffman.o
make -f ./scripts/Makefile.build obj=lib/lzma

lib/lzma/LzmaDec.o lib/lzma/LzmaTools.o
make -f ./scripts/Makefile.build obj=lib/lzo

lib/lzo/lzo1x_decompress.o
make -f ./scripts/Makefile.build obj=lib/zlib

lib/zlib/zlib.o
  arm-linux-gcc -Wp,-MD,lib/.display_options.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(display_options)"  -D"KBUILD_MODNAME=KBUILD_STR(display_options)" -c -o lib/display_options.o lib/display_options.c

lib/lzma/built-in.o lib/lzo/built-in.o lib/zlib/built-in.o lib/bzip2/built-in.o lib/crc7.o lib/crc8.o lib/crc16.o lib/gunzip.o lib/initcall.o lib/lmb.o lib/ldiv.o lib/net_utils.o lib/qsort.o lib/rc4.o lib/strmhz.o lib/rbtree.o lib/list_sort.o lib/hashtable.o lib/errno.o lib/display_options.o lib/crc32.o lib/ctype.o lib/div64.o lib/hang.o lib/linux_compat.o lib/linux_string.o lib/membuff.o lib/slre.o lib/string.o lib/time.o lib/vsprintf.o lib/panic.o lib/strto.o

   arm-linux-ld     -r -o lib/built-in.o lib/lzma/built-in.o lib/lzo/built-in.o lib/zlib/built-in.o lib/bzip2/built-in.o lib/crc7.o lib/crc8.o lib/crc16.o lib/gunzip.o lib/initcall.o lib/lmb.o lib/ldiv.o lib/net_utils.o lib/qsort.o lib/rc4.o lib/strmhz.o lib/rbtree.o lib/list_sort.o lib/hashtable.o lib/errno.o lib/display_options.o lib/crc32.o lib/ctype.o lib/div64.o lib/hang.o lib/linux_compat.o lib/linux_string.o lib/membuff.o lib/slre.o lib/string.o lib/time.o lib/vsprintf.o lib/panic.o lib/strto.o 
make -f ./scripts/Makefile.build obj=net

net/checksum.o net/arp.o net/bootp.o net/eth_legacy.o net/eth_common.o net/net.o net/nfs.o net/ping.o net/tftp.o
make -f ./scripts/Makefile.build obj=test

make -f ./scripts/Makefile.build obj=test/dm

make -f ./scripts/Makefile.build obj=examples
make -f ./scripts/Makefile.build obj=examples/standalone
  arm-linux-gcc -Wp,-MD,examples/standalone/.stubs.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -fno-toplevel-reorder -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(stubs)"  -D"KBUILD_MODNAME=KBUILD_STR(stubs)" -c -o examples/standalone/stubs.o examples/standalone/stubs.c
  arm-linux-ld     -r -o examples/standalone/libstubs.o examples/standalone/stubs.o
  arm-linux-gcc -Wp,-MD,examples/standalone/.hello_world.o.d  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h -D__KERNEL__ -D__UBOOT__ -Wall -Wstrict-prototypes -Wno-format-security -fno-builtin -ffreestanding -Os -fno-stack-protector -fno-delete-null-pointer-checks -g -Wno-format-nonliteral -fno-toplevel-reorder -D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t    -D"KBUILD_STR(s)=#s" -D"KBUILD_BASENAME=KBUILD_STR(hello_world)"  -D"KBUILD_MODNAME=KBUILD_STR(hello_world)" -c -o examples/standalone/hello_world.o examples/standalone/hello_world.c
  arm-linux-ld   -g -Ttext 0xc100000 -o examples/standalone/hello_world -e hello_world examples/standalone/hello_world.o examples/standalone/libstubs.o -L /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/armv4t -lgcc
  arm-linux-objcopy -O srec  examples/standalone/hello_world examples/standalone/hello_world.srec
  arm-linux-objcopy -O binary  examples/standalone/hello_world examples/standalone/hello_world.bin
  arm-linux-gcc -E -Wp,-MD,./.u-boot.lds.d -D__KERNEL__ -D__UBOOT__   -D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux  -mword-relocations  -fno-pic  -ffunction-sections -fdata-sections -fno-common -ffixed-r9  -msoft-float   -pipe -march=armv4t   -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -include ./include/u-boot/u-boot.lds.h -DCPUDIR=arch/arm/cpu/arm920t  -ansi -D__ASSEMBLY__ -x assembler-with-cpp -P -o u-boot.lds arch/arm/cpu/u-boot.lds
  arm-linux-ld   -pie  --gc-sections -Bstatic -Ttext 0x0 -o u-boot -T u-boot.lds arch/arm/cpu/arm920t/start.o --start-group  arch/arm/cpu/built-in.o  arch/arm/cpu/arm920t/built-in.o  arch/arm/lib/built-in.o  board/samsung/common/built-in.o  board/samsung/smdk2410/built-in.o  cmd/built-in.o  common/built-in.o  disk/built-in.o  drivers/built-in.o  drivers/dma/built-in.o  drivers/gpio/built-in.o  drivers/i2c/built-in.o  drivers/mmc/built-in.o  drivers/mtd/built-in.o  drivers/mtd/nand/built-in.o  drivers/mtd/onenand/built-in.o  drivers/mtd/spi/built-in.o  drivers/mtd/ubi/built-in.o  drivers/net/built-in.o  drivers/net/phy/built-in.o  drivers/pci/built-in.o  drivers/power/built-in.o  drivers/power/battery/built-in.o  drivers/power/fuel_gauge/built-in.o  drivers/power/mfd/built-in.o  drivers/power/pmic/built-in.o  drivers/power/regulator/built-in.o  drivers/serial/built-in.o  drivers/spi/built-in.o  drivers/usb/common/built-in.o  drivers/usb/dwc3/built-in.o  drivers/usb/emul/built-in.o  drivers/usb/eth/built-in.o  drivers/usb/gadget/built-in.o  drivers/usb/gadget/udc/built-in.o  drivers/usb/host/built-in.o  drivers/usb/musb-new/built-in.o  drivers/usb/musb/built-in.o  drivers/usb/phy/built-in.o  drivers/usb/ulpi/built-in.o  fs/built-in.o  lib/built-in.o  net/built-in.o  test/built-in.o  test/dm/built-in.o --end-group arch/arm/lib/eabi_compat.o  -L /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/armv4t -lgcc -Map u-boot.map
  arm-linux-objcopy --gap-fill=0xff  -j .text -j .secure_text -j .rodata -j .hash -j .data -j .got -j .got.plt -j .u_boot_list -j .rel.dyn -O srec u-boot u-boot.srec
  arm-linux-objcopy --gap-fill=0xff  -j .text -j .secure_text -j .rodata -j .hash -j .data -j .got -j .got.plt -j .u_boot_list -j .rel.dyn -O binary  u-boot u-boot-nodtb.bin
  cp u-boot-nodtb.bin u-boot.bin
  arm-linux-objdump -t u-boot > u-boot.sym
  arm-linux-gcc -E -Wp,-MD,./.u-boot.cfg.d -D__KERNEL__ -D__UBOOT__   -D__ARM__ -marm -mno-thumb-interwork  -mabi=aapcs-linux  -mword-relocations  -fno-pic  -ffunction-sections -fdata-sections -fno-common -ffixed-r9  -msoft-float   -pipe -march=armv4t   -Iinclude   -I./arch/arm/include -include ./include/linux/kconfig.h  -nostdinc -isystem /usr/local/arm/4.3.2/bin/../lib/gcc/arm-none-linux-gnueabi/4.3.2/include -include ./include/u-boot/u-boot.lds.h -DCPUDIR=arch/arm/cpu/arm920t  -ansi -DDO_DEPS_ONLY -D__ASSEMBLY__ -x assembler-with-cpp -P -dM -E -o u-boot.cfg include/config.h
View Code

我们大致看一下输出内容,主要包括以下两点:

  • 先利用./scripts/Makefile.build编译各个built-in.o目标文件;

  • 再将各个bult-in.o文件链接成u-boot;

二、make编译过程

make在编译过程中,会根据不用的obj,编译生成相应的xxx/.../xxxx/built-in.o文件。

make -f ./scripts/Makefile.build obj=目标路径  #执行目标下的Makefile生成build-in.o

然后由这些文件最终链接连接成u-boot文件:

 arm-linux-ld   -pie  --gc-sections -Bstatic -Ttext 0x0 -o u-boot -T u-boot.lds arch/arm/cpu/arm920t/start.o --sn.o  common/built-in.o  disk/built-in.o  drivers/built-in.o  drivers/dma/built-in.o  drivers/gpio/built-in.o  dribuilt-in.o  drivers/net/built-in.o  drivers/net/phy/built-in.o  drivers/pci/built-in.o  drivers/power/built-in.o rs/serial/built-in.o  drivers/spi/built-in.o  drivers/usb/common/built-in.o  drivers/usb/dwc3/built-in.o  drivers.o  drivers/usb/musb/built-in.o  drivers/usb/phy/built-in.o  drivers/usb/ulpi/built-in.o  fs/built-in.o  lib/buil -lgcc -Map u-boot.map

不知道你们有没有留意到吗,在make的编译过程中,有以下几个步骤:

make -f ./scripts/Makefile.build obj=arch/arm/cpu
make -f ./scripts/Makefile.build obj=arch/arm/cpu/arm920t
make -f ./scripts/Makefile.build obj=arch/arm/cpu/arm920t/s3c24x0

我们从最后一个来说,这里将会跳转到./script/Makefile.build文件中去执行,然后include obj路径下的Makefile文件,即arch/arm/cpu/arm920t/s3c24x0/Makefile。

2.1 arch/arm/cpu/arm920t/s3c24x0/Makefile

arch/arm/cpu/arm920t/s3c24x0/Makefile:

#
# (C) Copyright 2000-2006
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#
# SPDX-License-Identifier:    GPL-2.0+
#

obj-$(CONFIG_USE_IRQ) += interrupts.o
obj-$(CONFIG_DISPLAY_CPUINFO)    += cpu_info.o
obj-y    += speed.o
obj-y    += timer.o

obj-y是在./script/Makefile.build文件中定义:

obj-y :=

最终目标arch/arm/cpu/arm920t/s3c24x0/built-in.o依赖的obj-y如下:

  • arch/arm/cpu/arm920t/s3c24x0/cpu_info.o
  • arch/arm/cpu/arm920t/s3c24x0/speed.o
  • arch/arm/cpu/arm920t/s3c24x0/timer.o

2.2 arch/arm/cpu/arm920t/Makefile

同理,arch/arm/cpu/arm920t/Makefile:

#
# (C) Copyright 2000-2006
# Wolfgang Denk, DENX Software Engineering, wd@denx.de.
#
# SPDX-License-Identifier:    GPL-2.0+
#

extra-y    = start.o

obj-y    += cpu.o      # 1
obj-$(CONFIG_USE_IRQ)    += interrupts.o

obj-$(CONFIG_EP93XX) += ep93xx/
obj-$(CONFIG_IMX) += imx/
obj-$(CONFIG_S3C24X0) += s3c24x0/  #2 以%/结尾最终会被替换成%/built-in.o

# some files can only build in ARM mode

ifdef CONFIG_SYS_THUMB_BUILD
CFLAGS_cpu.o := -marm
endif

最终目标arch/arm/cpu/arm920t/built-in.o依赖的obj-y如下:

  • arch/arm/cpu/arm920t/cpu.o
  • arch/arm/cpu/arm920t/s3c24x0/built-in.o

2.3 arch/arm/cpu/Makefile

arch/arm/cpu/Makefile:

#
# SPDX-License-Identifier:    GPL-2.0+
#

obj- += dummy.o

最终obj-y为空,所以生成的arch/arm/cpu/built-in.o文件实际是空的。

2.4 ./scripts/Makefile.build

我们在之前介绍过,u-boot目标依赖于$(u-boot-main)、$(u-boot-init)、u-boot.lds。

u-boot-init := $(head-y)
u-boot-main := $(libs-y)

而libs-y由若干个以built-in.o结尾的文件组成,lib-y大致如下:

libs-y = lib/built-in.o fs/built-in.o net/built-in.o disk/built-in.o drivers/built-in.o drivers/dma/built-in.o drivers/gpio/built-in.o ...

而libs-y中的各个built-in.o文件由./scripts/Makefile.build编译而成:

ifneq ($(strip $(obj-y) $(obj-m) $(obj-) $(subdir-m) $(lib-target)),)
builtin-target := $(obj)/built-in.o
endif
$(builtin-target): $(obj-y) FORCE
    $(call if_changed,link_o_target)

 

比如make -f ./scripts/Makefile.build obj=arch/arm/cpu编译生成了arch/arm/cpu/build-in.o(builtin-target=arch/arm/cpu/built-in.o)。

而obj-y是由若干个.o目标文件组成,这里我将上面三条步骤中的obj-y输出,如下:

make -f ./scripts/Makefile.build obj=arch/arm/cpu
make -f ./scripts/Makefile.build obj=arch/arm/cpu/arm920t
make -f ./scripts/Makefile.build obj=arch/arm/cpu/arm920t/s3c24x0
---------------------------------------
arch/arm/cpu/arm920t/s3c24x0/cpu_info.o arch/arm/cpu/arm920t/s3c24x0/speed.o arch/arm/cpu/arm920t/s3c24x0/timer.o
arch/arm/cpu/arm920t/cpu.o arch/arm/cpu/arm920t/s3c24x0/built-in.o
不存在

obj-y依赖的.o文件又是怎么生成的,生成规则也是在./scripts/Makefile.build有定义:

$(obj)/%.o: $(src)/%.c $(recordmcount_source) FORCE
    $(call cmd,force_checksrc)
    $(call if_changed_rule,cc_o_c)

这里src可以看做和obj相同:

  • 当obj=arch/arm/cpu时,即定义了arch/arm/cpu/%.o文件的生成规则;
  • 当obj=arch/arm/cpu/arm920t时,即定义了arch/arm/cpu/arm920t/%.o文件的生成规则;
  • 当obj=arch/arm/cpu/arm920t/s3c24x0时,即定义了arch/arm/cpu/arm920t/s3c24x0/%.o文件的生成规则;

命令中的if_changed_rule函数定义在scripts/Kbuild.include文件中

# Usage: $(call if_changed_rule,foo)
# Will check if $(cmd_foo) or any of the prerequisites changed,
# and if so will execute $(rule_foo).
if_changed_rule = $(if $(strip $(any-prereq) $(arg-check) ),                 \
    @set -e;                                                             \
    $(rule_$(1)))

在./scripts/Makefile.build有如下定义:

define rule_cc_o_c
    $(call echo-cmd,checksrc) $(cmd_checksrc)              \
    $(call echo-cmd,cc_o_c) $(cmd_cc_o_c);                  \
    $(cmd_modversions)                          \
    $(call echo-cmd,record_mcount)                      \
    $(cmd_record_mcount)                          \
    scripts/basic/fixdep $(depfile) $@ '$(call make-cmd,cc_o_c)' >    \
                                                  $(dot-target).tmp;  \
    rm -f $(depfile);                          \
    mv -f $(dot-target).tmp $(dot-target).cmd
endef
cmd_cc_o_c = $(CC) $(c_flags) -c -o $@ $<

所以调用$(call if_changed_rule,cc_o_c)等价于执行cmd_cc_o_c。

这里我们重点介绍一下cmc_cc_o_c,因为这里在使用arm-linux-gcc编译时指定了c_flags参数(在顶层Makefile中定义):

   ifeq ($(dot-config),1)
   # Read in config
  -include include/config/auto.conf        # 1. 引入头文件

# Use UBOOTINCLUDE when you must reference the include/ directory.
# Needed to be compatible with the O= option
UBOOTINCLUDE    := \                     # 2.  变量定义
        -Iinclude \
        $(if $(KBUILD_SRC), -I$(srctree)/include) \
        $(if $(CONFIG_SYS_THUMB_BUILD), $(if $(CONFIG_HAS_THUMB2),, \
            -I$(srctree)/arch/$(ARCH)/thumb1/include),) \
        -I$(srctree)/arch/$(ARCH)/include \
        -include $(srctree)/include/linux/kconfig.h

NOSTDINC_FLAGS += -nostdinc -isystem $(shell $(CC) -print-file-name=include)
CHECKFLAGS     += $(NOSTDINC_FLAGS)

# FIX ME
cpp_flags := $(KBUILD_CPPFLAGS) $(PLATFORM_CPPFLAGS) $(UBOOTINCLUDE) \
                            $(NOSTDINC_FLAGS)
c_flags := $(KBUILD_CFLAGS) $(cpp_flags)

include/config/auto.conf.cmd是由fixdep在编译时生成的依赖文件,主要定义了常量,包含CPU信息、系统配置参数:

这里我们重点关注UBOOTINCLUDE和PLATFORM_CPPFLAGS:

(1) PLATFORM_CPPFLAGS是干嘛用的呢,之前我们介绍过built-in.o在生成时,依赖若干个.o目标文件,这些.o文件在生成时也会引入一些头文件,这些头文件一般都位于built-in.o同路径下得include 文件下,通过-I参数指定搜索的头路径,从而将这些头文件包含进来,比如arcm/arm/Makefile文件中指定了(需要注意的是这个追加的参数只有在编译arcm/arm/built-in.o时有效):

PLATFORM_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(machdirs))

(2) UBOOTINCLUDE 引入了./include、./arch/arm/include目录下的头文件、以及./include/linux/kconfig.h文件。其中./include/linux/kconfig.h文件引入了./include/generated/autoconf.h,包含了u-boot编译时所需要的各种宏的定义。

2.5 arch/arm/Makefile

#
# SPDX-License-Identifier:    GPL-2.0+
#

ifeq ($(CONFIG_SPL_BUILD)$(CONFIG_TEGRA),yy)
CONFIG_CPU_V7=
CONFIG_CPU_ARM720T=y
endif

# This selects which instruction set is used.
arch-$(CONFIG_CPU_ARM720T)    =-march=armv4
arch-$(CONFIG_CPU_ARM920T)    =-march=armv4t
arch-$(CONFIG_CPU_ARM926EJS)    =-march=armv5te
arch-$(CONFIG_CPU_ARM946ES)    =-march=armv4
arch-$(CONFIG_CPU_SA1100)    =-march=armv4
arch-$(CONFIG_CPU_PXA)        =
arch-$(CONFIG_CPU_ARM1136)    =-march=armv5
arch-$(CONFIG_CPU_ARM1176)    =-march=armv5t
arch-$(CONFIG_CPU_V7)        =$(call cc-option, -march=armv7-a, \
                 $(call cc-option, -march=armv7, -march=armv5))
arch-$(CONFIG_ARM64)        =-march=armv8-a

# Evaluate arch cc-option calls now
arch-y := $(arch-y)

# This selects how we optimise for the processor.
tune-$(CONFIG_CPU_ARM720T)    =-mtune=arm7tdmi
tune-$(CONFIG_CPU_ARM920T)    =
tune-$(CONFIG_CPU_ARM926EJS)    =
tune-$(CONFIG_CPU_ARM946ES)    =
tune-$(CONFIG_CPU_SA1100)    =-mtune=strongarm1100
tune-$(CONFIG_CPU_PXA)        =-mcpu=xscale
tune-$(CONFIG_CPU_ARM1136)    =
tune-$(CONFIG_CPU_ARM1176)    =
tune-$(CONFIG_CPU_V7)        =
tune-$(CONFIG_ARM64)        =

# Evaluate tune cc-option calls now
tune-y := $(tune-y)

PLATFORM_CPPFLAGS += $(arch-y) $(tune-y)

# Machine directory name.  This list is sorted alphanumerically
# by CONFIG_* macro name.
machine-$(CONFIG_ARCH_AT91)        += at91
machine-$(CONFIG_ARCH_BCM283X)        += bcm283x
machine-$(CONFIG_ARCH_DAVINCI)        += davinci
machine-$(CONFIG_ARCH_EXYNOS)        += exynos
machine-$(CONFIG_ARCH_HIGHBANK)        += highbank
machine-$(CONFIG_ARCH_KEYSTONE)        += keystone
# TODO: rename CONFIG_KIRKWOOD -> CONFIG_ARCH_KIRKWOOD
machine-$(CONFIG_KIRKWOOD)        += kirkwood
machine-$(CONFIG_ARCH_MVEBU)        += mvebu
# TODO: rename CONFIG_TEGRA -> CONFIG_ARCH_TEGRA
# TODO: rename CONFIG_ORION5X -> CONFIG_ARCH_ORION5X
machine-$(CONFIG_ORION5X)        += orion5x
machine-$(CONFIG_ARCH_S5PC1XX)        += s5pc1xx
machine-$(CONFIG_ARCH_SUNXI)        += sunxi
machine-$(CONFIG_ARCH_SNAPDRAGON)    += snapdragon
machine-$(CONFIG_ARCH_SOCFPGA)        += socfpga
machine-$(CONFIG_ARCH_ROCKCHIP)        += rockchip
machine-$(CONFIG_STM32)            += stm32
machine-$(CONFIG_TEGRA)            += tegra
machine-$(CONFIG_ARCH_UNIPHIER)        += uniphier
machine-$(CONFIG_ARCH_ZYNQ)        += zynq

machdirs := $(patsubst %,arch/arm/mach-%/,$(machine-y))    #取出$(machine-y)所有值,并替换追加arch/arm/mach-xx/  这里machdirs最终为空

PLATFORM_CPPFLAGS += $(patsubst %,-I$(srctree)/%include,$(machdirs))  #machdirs路径下的include文件  gcc编译时,头文件指定

libs-y += $(machdirs)

head-y := arch/arm/cpu/$(CPU)/start.o

ifeq ($(CONFIG_SPL_BUILD),y)
ifneq ($(CONFIG_SPL_START_S_PATH),)
head-y := $(CONFIG_SPL_START_S_PATH:"%"=%)/start.o
endif
endif

libs-y += arch/arm/cpu/$(CPU)/
libs-y += arch/arm/cpu/
libs-y += arch/arm/lib/

ifeq ($(CONFIG_SPL_BUILD),y)
ifneq (,$(CONFIG_MX23)$(CONFIG_MX28)$(CONFIG_MX35)$(filter $(SOC), mx25 mx27 mx5 mx6 mx7 mx31 mx35))
libs-y += arch/arm/imx-common/
endif
else
ifneq (,$(filter $(SOC), mx25 mx27 mx5 mx6 mx7 mx31 mx35 mxs vf610))
libs-y += arch/arm/imx-common/
endif
endif

ifneq (,$(filter $(SOC), kirkwood))
libs-y += arch/arm/mach-mvebu/
endif

# deprecated
-include $(machdirs)/config.mk

CONFIG_CPU_ARM920T=y在include/config/auto.conf文件中定义,而auto.conf文件是通过./srcipts/Makefile.build文件引入的:

[root@longmax2002 u-boot-2016.05]# grep "CONFIG_CPU_ARM920T" * -nR
arch/arm/mach-at91/Makefile:19:obj-$(CONFIG_CPU_ARM920T)        += arm920t/
arch/arm/Makefile:12:arch-$(CONFIG_CPU_ARM920T) =-march=armv4t
arch/arm/Makefile:28:tune-$(CONFIG_CPU_ARM920T) =
drivers/usb/host/ohci-hcd.c:53:#if defined(CONFIG_CPU_ARM920T) || \
include/config/auto.conf:65:CONFIG_CPU_ARM920T=y      # 这一条
include/generated/autoconf.h:67:#define CONFIG_CPU_ARM920T 1
u-boot.cfg:144:#define CONFIG_CPU_ARM920T 1

如果想知道machdirs的值,修改该Makefile文件,在变量后面追加:

print_machdirs::
        @echo "===================== WARNING ======================"
        @echo $(machdirs)
        @echo $(PLATFORM_CPPFLAGS)

在顶层执行make ARCH=arm CROSS_COMPILE=arm-linux- V=1  print_machdirs,可以获取变量的值:

其中machdirs为空,arm-linux-gcc编译参数PLATFORM_CPPFLAGS如下:

-D__ARM__ -marm -mno-thumb-interwork -mabi=aapcs-linux -mword-relocations -fno-pic -ffunction-sections -fdata-sections -fno-common -ffixed-r9 -msoft-float -pipe -march=armv4t

三、u-boot启动流程

想要分析启动流程,第一步就是分析链接文件,弄清楚程序入口是哪里。在分析Makefile中,u-boot的依赖中可以看到链接脚本文件是u-boot.lds,u-boot.lds依赖于$(LDSCRIPT)和prepare。

3.1 u.boot.lds

通过对u-boot源代码编译会在顶层目录生成u-boot.lds,打开u-boot.lds:

$(LDSCRIPT)变量值为arch/arm/cpu/u-boot.lds,定位到该文件:

#include <config.h>

OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
OUTPUT_ARCH(arm)
ENTRY(_start)
SECTIONS
{
#ifndef CONFIG_CMDLINE
    /DISCARD/ : { *(.u_boot_list_2_cmd_*) }
#endif
#if defined(CONFIG_ARMV7_SECURE_BASE) && defined(CONFIG_ARMV7_NONSEC)
    /*
     * If CONFIG_ARMV7_SECURE_BASE is true, secure code will not
     * bundle with u-boot, and code offsets are fixed. Secure zone
     * only needs to be copied from the loading address to
     * CONFIG_ARMV7_SECURE_BASE, which is the linking and running
     * address for secure code.
     *
     * If CONFIG_ARMV7_SECURE_BASE is undefined, the secure zone will
     * be included in u-boot address space, and some absolute address
     * were used in secure code. The absolute addresses of the secure
     * code also needs to be relocated along with the accompanying u-boot
     * code.
     *
     * So DISCARD is only for CONFIG_ARMV7_SECURE_BASE.
     */
    /DISCARD/ : { *(.rel._secure*) }
#endif
    . = 0x00000000;

    . = ALIGN(4);
    .text :
    {
        *(.__image_copy_start)
        *(.vectors)
        CPUDIR/start.o (.text*)
        *(.text*)
    }

#ifdef CONFIG_ARMV7_NONSEC

#ifndef CONFIG_ARMV7_SECURE_BASE
#define CONFIG_ARMV7_SECURE_BASE
#endif

    .__secure_start : {
        . = ALIGN(0x1000);
        *(.__secure_start)
    }

    .secure_text CONFIG_ARMV7_SECURE_BASE :
        AT(ADDR(.__secure_start) + SIZEOF(.__secure_start))
    {
        *(._secure.text)
    }

    . = LOADADDR(.__secure_start) +
        SIZEOF(.__secure_start) +
        SIZEOF(.secure_text);

    __secure_end_lma = .;
    .__secure_end : AT(__secure_end_lma) {
        *(.__secure_end)
        LONG(0x1d1071c);    /* Must output something to reset LMA */
    }
#endif

    . = ALIGN(4);
    .rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }

    . = ALIGN(4);
    .data : {
        *(.data*)
    }

    . = ALIGN(4);

    . = .;

    . = ALIGN(4);
    .u_boot_list : {
        KEEP(*(SORT(.u_boot_list*)));
    }

    . = ALIGN(4);

    .__efi_runtime_start : {
        *(.__efi_runtime_start)
    }

    .efi_runtime : {
        *(efi_runtime_text)
        *(efi_runtime_data)
    }

    .__efi_runtime_stop : {
        *(.__efi_runtime_stop)
    }

    .efi_runtime_rel_start :
    {
        *(.__efi_runtime_rel_start)
    }

    .efi_runtime_rel : {
        *(.relefi_runtime_text)
        *(.relefi_runtime_data)
    }

    .efi_runtime_rel_stop :
    {
        *(.__efi_runtime_rel_stop)
    }

    . = ALIGN(4);

    .image_copy_end :
    {
        *(.__image_copy_end)
    }

    .rel_dyn_start :
    {
        *(.__rel_dyn_start)
    }

    .rel.dyn : {
        *(.rel*)
    }

    .rel_dyn_end :
    {
        *(.__rel_dyn_end)
    }

    .end :
    {
        *(.__end)
    }

    _image_binary_end = .;

    /*
     * Deprecated: this MMU section is used by pxa at present but
     * should not be used by new boards/CPUs.
     */
    . = ALIGN(4096);
    .mmutable : {
        *(.mmutable)
    }

/*
 * Compiler-generated __bss_start and __bss_end, see arch/arm/lib/bss.c
 * __bss_base and __bss_limit are for linker only (overlay ordering)
 */

    .bss_start __rel_dyn_start (OVERLAY) : {
        KEEP(*(.__bss_start));
        __bss_base = .;
    }

    .bss __bss_base (OVERLAY) : {
        *(.bss*)
         . = ALIGN(4);
         __bss_limit = .;
    }

    .bss_end __bss_limit (OVERLAY) : {
        KEEP(*(.__bss_end));
    }

    .dynsym _image_binary_end : { *(.dynsym) }
    .dynbss : { *(.dynbss) }
    .dynstr : { *(.dynstr*) }
    .dynamic : { *(.dynamic*) }
    .plt : { *(.plt*) }
    .interp : { *(.interp*) }
    .gnu.hash : { *(.gnu.hash) }
    .gnu : { *(.gnu*) }
    .ARM.exidx : { *(.ARM.exidx*) }
    .gnu.linkonce.armexidx : { *(.gnu.linkonce.armexidx.*) }
}
View Code

其中:

(1) OUTPUT_FORMAT:指定输出可执行文件是elf格式,32位ARM指令,小端;

(2) OUTPUT_ARCH:指出输出可执行文件的平台是ARM;

(3) ENTRY:指定输出可执行文件的起始入口码段是_start,_start在arch/arm/cpu/arm920t/start.S;

(4) 0x00000000是程序的链接起始地点,arm-linux-ld最终生成的uboot.bin链接地址是从0x00000000开始;

(5) .text{}:声明该段是代码段,在此段中依次存放section(.__image_copy_start)、section(.vectors)、 section(start.o中所有的代码段 (.text*))、section(*(.text*))剩余的所有代码段。

*(.__image_copy_start):这里比较有意思的是section(.__image_copy_start),在arch/arm/lib/sections.c中有如下定义:

char __image_copy_start[0] __attribute__((section(".__image_copy_start")));

这是一个0长度的数组,GNU 对C的扩展,实际达到的目的就是section(.__image_copy_start)在链接时不占用链接地址空间,其后的section(.vectors)起始地址依然是0x00000000,然后在__image_copy_start存放了一个地址,也就是0x00000000,相当于创建一个位置标签;代表程序重定位(relocate)时拷贝的起始地址;

*(.vectors):字面上的意思就是向量段,在arch/arm/lib/vectors.S中定义了.verctos段:.section ".vectors", "ax";这是一个自定义的段标签的伪操作,含义是:定义一个段标签名为.vectors,且为允许、可执行段;

CPUDIR/start.o (.text*):CPUDIR在根目录的Makefile中定义,根据芯片;选择不同的start.S编译,编译出的start.o中.text段,链接到此处;在这里CPUDIR=arch/arm/cpu/arm920t;

*(.text*):剩余所有的代码都放到此段;

(6) .rodata{}:声明只读数据段,简称rodata段,存放常量,字符常量,const常量,据说还存放调试信息;

(7) .data{}:声明初始化数据段(Initialized data segment),简称data段,存放程序中已经初始化全局与初始化静态变量;

(8) .bss{}:声明未始化数据段(Uninitialized data segment),简称bss段,存放程序中未初始化全局与未初始化静态变量,该区域会在程序载入时由内核清零;

__image_copy_start、__image_copy_end用于u-boot搬移本身image到指定的ddr地址处;

__rel_dyn_start、__rel_dyn_end用于重定位代码;

__bss_start、__bss_end是bss段的开始、结束地址;

这几个变量在arch/arm/lib/sections.c中使用,定义一些全局变量作用于各个段的起始地址:

//C文件中利用这种方式把一个变量或者函数标记到指定段。
char __bss_start[0] __attribute__((section(".__bss_start")));
char __bss_end[0] __attribute__((section(".__bss_end")));
char __image_copy_start[0] __attribute__((section(".__image_copy_start")));
char __image_copy_end[0] __attribute__((section(".__image_copy_end")));
char __rel_dyn_start[0] __attribute__((section(".__rel_dyn_start")));
char __rel_dyn_end[0] __attribute__((section(".__rel_dyn_end")));
char __secure_start[0] __attribute__((section(".__secure_start")));
char __secure_end[0] __attribute__((section(".__secure_end")));

3.2 vectors(中断向量表)

我们接下来分析代码,程序的第一条指令就是在arch/arm/lib/vectors.S中。

/*
 *  vectors - Generic ARM exception table code
 *
 *  Copyright (c) 1998    Dan Malek <dmalek@jlc.net>
 *  Copyright (c) 1999    Magnus Damm <kieraypc01.p.y.kie.era.ericsson.se>
 *  Copyright (c) 2000    Wolfgang Denk <wd@denx.de>
 *  Copyright (c) 2001    Alex Züpke <azu@sysgo.de>
 *  Copyright (c) 2001    Marius Gröger <mag@sysgo.de>
 *  Copyright (c) 2002    Alex Züpke <azu@sysgo.de>
 *  Copyright (c) 2002    Gary Jennejohn <garyj@denx.de>
 *  Copyright (c) 2002    Kyle Harris <kharris@nexus-tech.net>
 *
 * SPDX-License-Identifier:    GPL-2.0+
 */

#include <config.h>

/*
 *************************************************************************
 *
 * Symbol _start is referenced elsewhere, so make it global
 *
 *************************************************************************
 */

.globl _start                 //声明__start全局符号,这个符号会在lds链接脚本中使用

/*
 *************************************************************************
 *
 * Vectors have their own section so linker script can map them easily
 *
 *************************************************************************
 */

    .section ".vectors", "ax"

/*
 *************************************************************************
 *
 * Exception vectors as described in ARM reference manuals
 *
 * Uses indirect branch to allow reaching handlers anywhere in memory.
 *
 *************************************************************************
 */

_start:

#ifdef CONFIG_SYS_DV_NOR_BOOT_CFG
    .word    CONFIG_SYS_DV_NOR_BOOT_CFG
#endif

    b    reset
    ldr    pc, _undefined_instruction
    ldr    pc, _software_interrupt
    ldr    pc, _prefetch_abort
    ldr    pc, _data_abort
    ldr    pc, _not_used
    ldr    pc, _irq
    ldr    pc, _fiq

/*
 *************************************************************************
 *
 * Indirect vectors table
 *
 * Symbols referenced here must be defined somewhere else
 *
 *************************************************************************
 */

    .globl    _undefined_instruction
    .globl    _software_interrupt
    .globl    _prefetch_abort
    .globl    _data_abort
    .globl    _not_used
    .globl    _irq
    .globl    _fiq

_undefined_instruction:    .word undefined_instruction
_software_interrupt:    .word software_interrupt
_prefetch_abort:    .word prefetch_abort
_data_abort:        .word data_abort
_not_used:        .word not_used
_irq:            .word irq
_fiq:            .word fiq

    .balignl 16,0xdeadbeef

/*
 *************************************************************************
 *
 * Interrupt handling
 *
 *************************************************************************
 */

/* SPL interrupt handling: just hang */

#ifdef CONFIG_SPL_BUILD

    .align    5
undefined_instruction:
software_interrupt:
prefetch_abort:
data_abort:
not_used:
irq:
fiq:

1:
    bl    1b            /* hang and never return */

#else    /* !CONFIG_SPL_BUILD */

/* IRQ stack memory (calculated at run-time) + 8 bytes */
.globl IRQ_STACK_START_IN
IRQ_STACK_START_IN:
    .word    0x0badc0de

#ifdef CONFIG_USE_IRQ
/* IRQ stack memory (calculated at run-time) */
.globl IRQ_STACK_START
IRQ_STACK_START:
    .word    0x0badc0de

/* IRQ stack memory (calculated at run-time) */
.globl FIQ_STACK_START
FIQ_STACK_START:
    .word 0x0badc0de

#endif /* CONFIG_USE_IRQ */

@
@ IRQ stack frame.
@
#define S_FRAME_SIZE    72

#define S_OLD_R0    68
#define S_PSR        64
#define S_PC        60
#define S_LR        56
#define S_SP        52

#define S_IP        48
#define S_FP        44
#define S_R10        40
#define S_R9        36
#define S_R8        32
#define S_R7        28
#define S_R6        24
#define S_R5        20
#define S_R4        16
#define S_R3        12
#define S_R2        8
#define S_R1        4
#define S_R0        0

#define MODE_SVC 0x13
#define I_BIT     0x80

/*
 * use bad_save_user_regs for abort/prefetch/undef/swi ...
 * use irq_save_user_regs / irq_restore_user_regs for IRQ/FIQ handling
 */

    .macro    bad_save_user_regs
    @ carve out a frame on current user stack
    sub    sp, sp, #S_FRAME_SIZE
    stmia    sp, {r0 - r12}    @ Save user registers (now in svc mode) r0-r12
    ldr    r2, IRQ_STACK_START_IN
    @ get values for "aborted" pc and cpsr (into parm regs)
    ldmia    r2, {r2 - r3}
    add    r0, sp, #S_FRAME_SIZE        @ grab pointer to old stack
    add    r5, sp, #S_SP
    mov    r1, lr
    stmia    r5, {r0 - r3}    @ save sp_SVC, lr_SVC, pc, cpsr
    mov    r0, sp        @ save current stack into r0 (param register)
    .endm

    .macro    irq_save_user_regs
    sub    sp, sp, #S_FRAME_SIZE
    stmia    sp, {r0 - r12}            @ Calling r0-r12
    @ !!!! R8 NEEDS to be saved !!!! a reserved stack spot would be good.
    add    r8, sp, #S_PC
    stmdb    r8, {sp, lr}^        @ Calling SP, LR
    str    lr, [r8, #0]        @ Save calling PC
    mrs    r6, spsr
    str    r6, [r8, #4]        @ Save CPSR
    str    r0, [r8, #8]        @ Save OLD_R0
    mov    r0, sp
    .endm

    .macro    irq_restore_user_regs
    ldmia    sp, {r0 - lr}^            @ Calling r0 - lr
    mov    r0, r0
    ldr    lr, [sp, #S_PC]            @ Get PC
    add    sp, sp, #S_FRAME_SIZE
    subs    pc, lr, #4        @ return & move spsr_svc into cpsr
    .endm

    .macro get_bad_stack
    ldr    r13, IRQ_STACK_START_IN        @ setup our mode stack

    str    lr, [r13]    @ save caller lr in position 0 of saved stack
    mrs    lr, spsr    @ get the spsr
    str    lr, [r13, #4]    @ save spsr in position 1 of saved stack
    mov    r13, #MODE_SVC    @ prepare SVC-Mode
    @ msr    spsr_c, r13
    msr    spsr, r13    @ switch modes, make sure moves will execute
    mov    lr, pc        @ capture return pc
    movs    pc, lr        @ jump to next instruction & switch modes.
    .endm

    .macro get_irq_stack            @ setup IRQ stack
    ldr    sp, IRQ_STACK_START
    .endm

    .macro get_fiq_stack            @ setup FIQ stack
    ldr    sp, FIQ_STACK_START
    .endm

/*
 * exception handlers
 */

    .align  5
undefined_instruction:
    get_bad_stack
    bad_save_user_regs
    bl    do_undefined_instruction

    .align    5
software_interrupt:
    get_bad_stack
    bad_save_user_regs
    bl    do_software_interrupt

    .align    5
prefetch_abort:
    get_bad_stack
    bad_save_user_regs
    bl    do_prefetch_abort

    .align    5
data_abort:
    get_bad_stack
    bad_save_user_regs
    bl    do_data_abort

    .align    5
not_used:
    get_bad_stack
    bad_save_user_regs
    bl    do_not_used

#ifdef CONFIG_USE_IRQ

    .align    5
irq:
    get_irq_stack
    irq_save_user_regs
    bl    do_irq
    irq_restore_user_regs

    .align    5
fiq:
    get_fiq_stack
    /* someone ought to write a more effiction fiq_save_user_regs */
    irq_save_user_regs
    bl    do_fiq
    irq_restore_user_regs

#else

    .align    5
irq:
    get_bad_stack
    bad_save_user_regs
    bl    do_irq

    .align    5
fiq:
    get_bad_stack
    bad_save_user_regs
    bl    do_fiq

#endif /* CONFIG_USE_IRQ */

#endif    /* CONFIG_SPL_BUILD */
View Code

0x~0x1C地址定义了中断向量表,以地址0x04为例,将[pc,#20]地址的值加载到PC,也就是跳转到0x60处执行,即执行undefined_instruction中断处理程序。

3.3 reset(复位)

CPU上电后,执行第一条命令b reset。跳转到arch/arm/cpu/arm920t/start.S文件执行。

/*
 *  armboot - Startup Code for ARM920 CPU-core
 *
 *  Copyright (c) 2001  Marius Gröger <mag@sysgo.de>
 *  Copyright (c) 2002  Alex Züpke <azu@sysgo.de>
 *  Copyright (c) 2002  Gary Jennejohn <garyj@denx.de>
 *
 * SPDX-License-Identifier: GPL-2.0+
 */

#include <asm-offsets.h>
#include <common.h>
#include <config.h>

/*
 *************************************************************************
 *
 * Startup Code (called from the ARM reset exception vector)
 *
 * do important init only if we don't start from memory!
 * relocate armboot to ram
 * setup stack
 * jump to second stage
 *
 *************************************************************************
 */

    .globl  reset

reset:
    /*
     * set the cpu to SVC32 mode    1. 设置为SVC模式
     */
    mrs r0, cpsr
    bic r0, r0, #0x1f
    orr r0, r0, #0xd3
    msr cpsr, r0    

#if defined(CONFIG_AT91RM9200DK) || defined(CONFIG_AT91RM9200EK)
    /*
     * relocate exception table
     */
    ldr r0, =_start
    ldr r1, =0x0
    mov r2, #16
copyex:
    subs    r2, r2, #1
    ldr r3, [r0], #4
    str r3, [r1], #4
    bne copyex
#endif

#ifdef CONFIG_S3C24X0
    /* turn off the watchdog */

# if defined(CONFIG_S3C2400)
#  define pWTCON    0x15300000
#  define INTMSK    0x14400008  /* Interrupt-Controller base addresses */
#  define CLKDIVN   0x14800014  /* clock divisor register */
#else
#  define pWTCON    0x53000000  /* 看门狗控制寄存器地址 */
#  define INTMSK    0x4A000008  /* Interrupt-Controller base addresses */
#  define INTSUBMSK 0x4A00001C
#  define CLKDIVN   0x4C000014  /* clock divisor register */
# endif

    ldr r0, =pWTCON        /* 2. 关看门狗 */
    mov r1, #0x0
    str r1, [r0]

    /*
     * mask all IRQs by setting all bits in the INTMR - default
     */
    mov r1, #0xffffffff    /* 3. 屏蔽中断 */
    ldr r0, =INTMSK
    str r1, [r0]
# if defined(CONFIG_S3C2410)
    ldr r1, =0x3ff
    ldr r0, =INTSUBMSK
    str r1, [r0]
# endif

    /* FCLK:HCLK:PCLK = 1:2:4 */
    /* default FCLK is 120 MHz ! */
    ldr r0, =CLKDIVN      /* 4. 设置分频系数,未设置时钟频率 */
    mov r1, #3
    str r1, [r0]
#endif  /* CONFIG_S3C24X0 */

    /*
     * we do sys-critical inits only at reboot,
     * not when booting from ram!
     */
#ifndef CONFIG_SKIP_LOWLEVEL_INIT
    bl  cpu_init_crit    /*  5. 跳到cpu_init_crit函数 */
#endif

    bl  _main           /* 6. 进入arch/arm/lib/crt0.S的_main函数,进行其他初始化 */

/*------------------------------------------------------------------------------*/

    .globl  c_runtime_cpu_setup
c_runtime_cpu_setup:

    mov pc, lr

/*
 *************************************************************************
 *
 * CPU_init_critical registers
 *
 * setup important registers
 * setup memory timing
 *
 *************************************************************************
 */


#ifndef CONFIG_SKIP_LOWLEVEL_INIT
cpu_init_crit:
    /*
     * flush v4 I/D caches      [1]. 清除cache
     */
    mov r0, #0
    mcr p15, 0, r0, c7, c7, 0   /* flush v3/v4 cache */
    mcr p15, 0, r0, c8, c7, 0   /* flush v4 TLB */

    /*
     * disable MMU stuff and caches  [2]. 禁止MMU
     */
    mrc p15, 0, r0, c1, c0, 0
    bic r0, r0, #0x00002300 @ clear bits 13, 9:8 (--V- --RS)
    bic r0, r0, #0x00000087 @ clear bits 7, 2:0 (B--- -CAM)
    orr r0, r0, #0x00000002 @ set bit 1 (A) Align
    orr r0, r0, #0x00001000 @ set bit 12 (I) I-Cache
    mcr p15, 0, r0, c1, c0, 0

#ifndef CONFIG_SKIP_LOWLEVEL_INIT_ONLY
    /*
     * before relocating, we have to setup RAM timing
     * because memory timing is board-dependend, you will
     * find a lowlevel_init.S in your board directory.
     */
    mov ip, lr

    bl  lowlevel_init          /* [3]. 进入board/samsung/smdk2410/lowlevel_init.S执行*/
                               /*     设置内存控制寄存器时序参数 */
    mov lr, ip
#endif
    mov pc, lr
#endif /* CONFIG_SKIP_LOWLEVEL_INIT */
View Code

我们总结以下start.S文件主要做了哪些事情:

(1) 开启SVC模式,关闭fiq、irq中断;

(2) 关闭看门狗;

(3) 屏蔽所有中断;

(4) 设置系统时钟;

(5) 执行cpu_init_crit函数;

  • 关闭关闭MMU和cache;
  • 执行lowlevel_init函数(board/samsung/smdk2410/lowlevel_init.S),初始化SDRAM;

(6) 执行_main(arch/arm/lib/crt0.S);

3.4 跳转_main

这块代码也比较多,这里就一点一点的展示,并进行讲解。文件开头就是引入一些有文件

#include <config.h>
#include <asm-offsets.h>
#include <linux/linkage.h>
#ifdef CONFIG_CPU_V7M
#include <asm/armv7m.h>
#endif

接着,是一堆对文件的描述:

/*
 * This file handles the target-independent stages of the U-Boot
 * start-up where a C runtime environment is needed. Its entry point
 * is _main and is branched into from the target's start.S file.
 *
 * _main execution sequence is:
 *
 * 1. Set up initial environment for calling board_init_f().
 *    This environment only provides a stack and a place to store
 *    the GD ('global data') structure, both located in some readily
 *    available RAM (SRAM, locked cache...). In this context, VARIABLE
 *    global data, initialized or not (BSS), are UNAVAILABLE; only
 *    CONSTANT initialized data are available. GD should be zeroed
 *    before board_init_f() is called.
 *
 * 2. Call board_init_f(). This function prepares the hardware for
 *    execution from system RAM (DRAM, DDR...) As system RAM may not
 *    be available yet, , board_init_f() must use the current GD to
 *    store any data which must be passed on to later stages. These
 *    data include the relocation destination, the future stack, and
 *    the future GD location.
 *
 * 3. Set up intermediate environment where the stack and GD are the
 *    ones allocated by board_init_f() in system RAM, but BSS and
 *    initialized non-const data are still not available.
 *
 * 4a.For U-Boot proper (not SPL), call relocate_code(). This function
 *    relocates U-Boot from its current location into the relocation
 *    destination computed by board_init_f().
 *
 * 4b.For SPL, board_init_f() just returns (to crt0). There is no
 *    code relocation in SPL.
 *
 * 5. Set up final environment for calling board_init_r(). This
 *    environment has BSS (initialized to 0), initialized non-const
 *    data (initialized to their intended value), and stack in system
 *    RAM (for SPL moving the stack and GD into RAM is optional - see
 *    CONFIG_SPL_STACK_R). GD has retained values set by board_init_f().
 *
 * 6. For U-Boot proper (not SPL), some CPUs have some work left to do
 *    at this point regarding memory, so call c_runtime_cpu_setup.
 *
 * 7. Branch to board_init_r().
 *
 * For more information see 'Board Initialisation Flow in README.
 */

这里作者罗列了几条内容,这里我大致翻译一下:

(1) 函数首先设置栈,然后在栈底预留一定的内存空间给gd_t结构体并清零,用来存放全局参数, 然后调用board_init_f();这里作者提到在当前上下文,已经初始化的全局变量(位于.data段)或者是未初始化的全局变量(位于.bss段)是无法访问到的,这主要是因为还没将代码从NAND或者NOR拷贝到SDRAM;

(2) 调用board_init_f(),这个函数调用一系列函数来初始化硬件以使程序能够在SDRAM中执行,且这个函数需要使用设置好的gd_t结构体来存放初始化中的各个参数以备后用,比如:重定位地址,重定位后的栈地址、重定位后的gd_t的地址;

(3) 由于bss段还没初始化,board_init_f()设置gd_t时不能使用全局变量、静态变量等, 所以设置的环境参数不是最终的;

(4) smdk2410.h没有定义SPL,所以会在_main()函数中根据board_init_f()设置的重定位参数进行代码重定位;

(5) 重定位后,bss和non-const data都被初始化了,在进入board_init_r()函数之前应先设置最终的环境参数;

(6) 调用board_init_r()函数;

最后,才是代码,这段代码主要就是设置C语言运行环境,并调用board_init_f跳转到C语言执行。

/*
 * entry point of crt0 sequence
 */

ENTRY(_main)

/*
 * Set up initial C runtime environment and call board_init_f(0).
 */

#if defined(CONFIG_SPL_BUILD) && defined(CONFIG_SPL_STACK)
    ldr sp, =(CONFIG_SPL_STACK)           // 0x1000  
#else
    ldr sp, =(CONFIG_SYS_INIT_SP_ADDR)    //1. 设置栈    0x30000f50
#endif
#if defined(CONFIG_CPU_V7M) /* v7M forbids using SP as BIC destination */
    mov r3, sp
    bic r3, r3, #7
    mov sp, r3
#else
    bic sp, sp, #7  /* 8-byte alignment for ABI compliance */
#endif
    mov r0, sp
    bl  board_init_f_alloc_reserve    //2. 为gd_t结构体保留空间
    mov sp, r0
    /* set up gd here, outside any C code */
    mov r9, r0
    bl  board_init_f_init_reserve    //3. 初始化gd_t(清零)
                    //gd_t的地址存在r9寄存器中,结构体中存放的是全局参数

    mov r0, #0
    bl  board_init_f           //4. 进入board_init_f进行各种初始化,分配SDRAM内存空间,填充进gd_t结构体中

smdk2410.h文件中没有定义SPL,所以sp设置为CONFIG_SYS_INIT_SP_ADDR,如果使用了SPL,那么sp将被设置为片内SRAM的最顶部。

#define PHYS_SDRAM_1        0x30000000 /* SDRAM Bank #1 */
#define CONFIG_SYS_SDRAM_BASE    PHYS_SDRAM_1
#define CONFIG_SYS_INIT_SP_ADDR    (CONFIG_SYS_SDRAM_BASE + 0x1000 - \
                GENERATED_GBL_DATA_SIZE)
3.4.1 board_init_f_alloc_reserve

board_init_f_alloc_reserve函数用于从“栈顶部”地址分配保留空间,用作全局变量gd_t,并返回已分配空间的“栈底部”地址。位于common/init/board_init.c文件中:

/*
 * Allocate reserved space for use as 'globals' from 'top' address and
 * return 'bottom' address of allocated space
 *
 * Notes:
 *
 * Actual reservation cannot be done from within this function as
 * it requires altering the C stack pointer, so this will be done by
 * the caller upon return from this function.
 *
 * IMPORTANT:
 *
 * Alignment constraints may differ for each 'chunk' allocated. For now:
 *
 * - GD is aligned down on a 16-byte boundary
 *
 *  - the early malloc arena is not aligned, therefore it follows the stack
 *   alignment constraint of the architecture for which we are bulding.
 *
 *  - GD is allocated last, so that the return value of this functions is
 *   both the bottom of the reserved area and the address of GD, should
 *   the calling context need it.
 */

ulong board_init_f_alloc_reserve(ulong top)
{
        /* Reserve early malloc arena */
#if defined(CONFIG_SYS_MALLOC_F)
        top -= CONFIG_SYS_MALLOC_F_LEN;
#endif
        /* LAST : reserve GD (rounded up to a multiple of 16 bytes) */
        top = rounddown(top-sizeof(struct global_data), 16);

        return top;
}

这里top传入的为sp的值,并在栈顶底预留了global_data结构体大小的数据,然后设置栈底为16字节对齐,同时将gd_t结构体的起始地址保存到r9寄存器。

DECLARE_GLOBAL_DATA_PTR定义了一个gd_t全局数据结构的指针,这个指针存放在指定的寄存器r9中。这个声明也避免了编译器把r9分配给其他的变量,任何想要访问访问全局数据区的代码,只要代码开头加DECLARE_GLOBAL_DATA_PTR一行代码,然后就可以使用gd指针来访问全局数据区了。

#define DECLARE_GLOBAL_DATA_PTR        register volatile gd_t *gd asm ("r9")

u-boot启动内核时要给内核传递参数,这时就要使用gd_t,结构体中的信息来设置标记列表。

3.4.2 board_init_f_init_reserve

board_init_f_init_reserve该函数用于初始化gd_t内存空间内容为0。

void board_init_f_init_reserve(ulong base)
{
    struct global_data *gd_ptr;
#ifndef _USE_MEMCPY
    int *ptr;
#endif

    /*
     * clear GD entirely and set it up.
     * Use gd_ptr, as gd may not be properly set yet.
     */

    gd_ptr = (struct global_data *)base;
    /* zero the area */
#ifdef _USE_MEMCPY
    memset(gd_ptr, '\0', sizeof(*gd));   #*gd大小0xa8
#else
    for (ptr = (int *)gd_ptr; ptr < (int *)(gd_ptr + 1); )
        *ptr++ = 0;
#endif
    /* set GD unless architecture did it already */
#if !defined(CONFIG_ARM)
    arch_setup_gd(gd_ptr);
#endif
    /* next alloc will be higher by one GD plus 16-byte alignment */
    base += roundup(sizeof(struct global_data), 16);

    /*
     * record early malloc arena start.
     * Use gd as it is now properly set for all architectures.
     */

#if defined(CONFIG_SYS_MALLOC_F)
    /* go down one 'early malloc arena' */
    gd->malloc_base = base;
    /* next alloc will be higher by one 'early malloc arena' size */
    base += CONFIG_SYS_MALLOC_F_LEN;
#endif
}

指定位置base作结构体gd的存放地。

四、重要头文件

在u-boot启动流程中有两个比较重要的有文件,一个是include/config.h,另一个是include/configs/smdk2410.h。

4.1 include/config.h

start.S文件的开始,#include <config.h>,config.h从哪里来的呢?在上一小节中我们已经介绍了Make在编译过程中,arm-linux-gcc指定了头文件路径:

  • UBOOTINCLUDE:引入了./include、./arch/arm/include目录下的头文件、以及./include/linux/kconfig.h文件。
  • PLATFORM_CPPFLAGS

至于这里写成#include<config.h>而不是#include<include/config.h>是因为arm-linux-gcc在编译的时候通过-I参数指定了搜索头文件的目录有./include:

include/config.h文件在make smdk2410_config时创建,主要包含以下信息:

/* Automatically generated - do not edit */
#define CONFIG_BOARDDIR board/samsung/smdk2410
#include <config_defaults.h>
#include <config_uncmd_spl.h>
#include <configs/smdk2410.h>
#include <asm/config.h>
#include <config_fallbacks.h>

#include <configs/smdk2410.h> 从这里可以看出在include/configs目录下,包含smdk2410.h文件,如果在board目录下新建一个开发板的目录,则在include/configs目录下要创建一个.h文件,里面存放的开发板配置信息。

#include <asm/config.h>来自arch/arm/include/asm目录:

/*
 * Copyright 2009 Freescale Semiconductor, Inc.
 *
 * SPDX-License-Identifier:    GPL-2.0+
 */

#ifndef _ASM_CONFIG_H_
#define _ASM_CONFIG_H_

#define CONFIG_LMB
#define CONFIG_SYS_BOOT_RAMDISK_HIGH

#ifdef CONFIG_ARM64
#define CONFIG_PHYS_64BIT
#define CONFIG_STATIC_RELA
#endif

#if defined(CONFIG_LS102XA) || \
    defined(CONFIG_CPU_PXA27X) || \
    defined(CONFIG_CPU_MONAHANS) || \
    defined(CONFIG_CPU_PXA25X) || \
    defined(CONFIG_FSL_LAYERSCAPE)
#include <asm/arch/config.h>
#endif

#endif

4.2 include/configs/smdk2410.h

这个文件是一个特定开发板或者硬件平台的配置文件,每个支持的硬件平台或开发板在u-boot源码中通常都有一个相应的配置头文件。

这里主要用来配置编译u-boot时是否启用某些功能,比如网卡,LCD等,如果定义了,那么将会编译相关模块的代码。

/*
 * (C) Copyright 2002
 * Sysgo Real-Time Solutions, GmbH <www.elinos.com>
 * Marius Groeger <mgroeger@sysgo.de>
 * Gary Jennejohn <garyj@denx.de>
 * David Mueller <d.mueller@elsoft.ch>
 *
 * Configuation settings for the SAMSUNG SMDK2410 board.
 *
 * SPDX-License-Identifier:    GPL-2.0+
 */

#ifndef __CONFIG_H
#define __CONFIG_H

/*
 * High Level Configuration Options
 * (easy to change)
 */
#define CONFIG_S3C24X0        /* This is a SAMSUNG S3C24x0-type SoC */
#define CONFIG_S3C2410        /* specifically a SAMSUNG S3C2410 SoC */
#define CONFIG_SMDK2410        /* on a SAMSUNG SMDK2410 Board */

#define CONFIG_SYS_TEXT_BASE    0x0

#define CONFIG_SYS_ARM_CACHE_WRITETHROUGH

/* input clock of PLL (the SMDK2410 has 12MHz input clock) */
#define CONFIG_SYS_CLK_FREQ    12000000

#define CONFIG_CMDLINE_TAG    /* enable passing of ATAGs */
#define CONFIG_SETUP_MEMORY_TAGS
#define CONFIG_INITRD_TAG

/*
 * Hardware drivers
 */
#define CONFIG_CS8900        /* we have a CS8900 on-board */
#define CONFIG_CS8900_BASE    0x19000300
#define CONFIG_CS8900_BUS16    /* the Linux driver does accesses as shorts */

/*
 * select serial console configuration
 */
#define CONFIG_S3C24X0_SERIAL
#define CONFIG_SERIAL1        1    /* we use SERIAL 1 on SMDK2410 */

/************************************************************
 * USB support (currently only works with D-cache off)
 ************************************************************/
#define CONFIG_USB_OHCI
#define CONFIG_USB_OHCI_S3C24XX
#define CONFIG_USB_KEYBOARD
#define CONFIG_USB_STORAGE
#define CONFIG_DOS_PARTITION

/************************************************************
 * RTC
 ************************************************************/
#define CONFIG_RTC_S3C24X0

#define CONFIG_BAUDRATE        115200

/*
 * BOOTP options
 */
#define CONFIG_BOOTP_BOOTFILESIZE
#define CONFIG_BOOTP_BOOTPATH
#define CONFIG_BOOTP_GATEWAY
#define CONFIG_BOOTP_HOSTNAME

/*
 * Command line configuration.
 */
#define CONFIG_CMD_BSP
#define CONFIG_CMD_DATE
#define CONFIG_CMD_NAND
#define CONFIG_CMD_REGINFO

#define CONFIG_CMDLINE_EDITING

/* autoboot */
#define CONFIG_BOOTDELAY    5
#define CONFIG_BOOT_RETRY_TIME    -1
#define CONFIG_RESET_TO_RETRY
#define CONFIG_ZERO_BOOTDELAY_CHECK

#define CONFIG_NETMASK        255.255.255.0
#define CONFIG_IPADDR        10.0.0.110
#define CONFIG_SERVERIP        10.0.0.1

#if defined(CONFIG_CMD_KGDB)
#define CONFIG_KGDB_BAUDRATE    115200    /* speed to run kgdb serial port */
#endif

/*
 * Miscellaneous configurable options
 */
#define CONFIG_SYS_LONGHELP        /* undef to save memory */
#define CONFIG_SYS_CBSIZE    256
/* Print Buffer Size */
#define CONFIG_SYS_PBSIZE    (CONFIG_SYS_CBSIZE + \
                sizeof(CONFIG_SYS_PROMPT)+16)
#define CONFIG_SYS_MAXARGS    16
#define CONFIG_SYS_BARGSIZE    CONFIG_SYS_CBSIZE

#define CONFIG_DISPLAY_CPUINFO                /* Display cpu info */

#define CONFIG_SYS_MEMTEST_START    0x30000000    /* memtest works on */
#define CONFIG_SYS_MEMTEST_END        0x33F00000    /* 63 MB in DRAM */

#define CONFIG_SYS_LOAD_ADDR        0x30800000

/* support additional compression methods */
#define CONFIG_BZIP2
#define CONFIG_LZO
#define CONFIG_LZMA

/*-----------------------------------------------------------------------
 * Physical Memory Map
 */
#define CONFIG_NR_DRAM_BANKS    1          /* we have 1 bank of DRAM */
#define PHYS_SDRAM_1        0x30000000 /* SDRAM Bank #1 */
#define PHYS_SDRAM_1_SIZE    0x04000000 /* 64 MB */

#define PHYS_FLASH_1        0x00000000 /* Flash Bank #0 */

#define CONFIG_SYS_FLASH_BASE    PHYS_FLASH_1

/*-----------------------------------------------------------------------
 * FLASH and environment organization
 */

#define CONFIG_SYS_FLASH_CFI
#define CONFIG_FLASH_CFI_DRIVER
#define CONFIG_FLASH_CFI_LEGACY
#define CONFIG_SYS_FLASH_LEGACY_512Kx16
#define CONFIG_FLASH_SHOW_PROGRESS    45

#define CONFIG_SYS_MAX_FLASH_BANKS    1
#define CONFIG_SYS_FLASH_BANKS_LIST     { CONFIG_SYS_FLASH_BASE }
#define CONFIG_SYS_MAX_FLASH_SECT    (19)

#define CONFIG_ENV_ADDR            (CONFIG_SYS_FLASH_BASE + 0x070000)
#define CONFIG_ENV_IS_IN_FLASH
#define CONFIG_ENV_SIZE            0x10000
/* allow to overwrite serial and ethaddr */
#define CONFIG_ENV_OVERWRITE

/*
 * Size of malloc() pool
 * BZIP2 / LZO / LZMA need a lot of RAM
 */
#define CONFIG_SYS_MALLOC_LEN    (4 * 1024 * 1024)

#define CONFIG_SYS_MONITOR_LEN    (448 * 1024)
#define CONFIG_SYS_MONITOR_BASE    CONFIG_SYS_FLASH_BASE

/*
 * NAND configuration
 */
#ifdef CONFIG_CMD_NAND
#define CONFIG_NAND_S3C2410
#define CONFIG_SYS_S3C2410_NAND_HWECC
#define CONFIG_SYS_MAX_NAND_DEVICE    1
#define CONFIG_SYS_NAND_BASE        0x4E000000
#endif

/*
 * File system
 */
#define CONFIG_CMD_UBI
#define CONFIG_CMD_UBIFS
#define CONFIG_CMD_MTDPARTS
#define CONFIG_MTD_DEVICE
#define CONFIG_MTD_PARTITIONS
#define CONFIG_YAFFS2
#define CONFIG_RBTREE

/* additions for new relocation code, must be added to all boards */
#define CONFIG_SYS_SDRAM_BASE    PHYS_SDRAM_1
#define CONFIG_SYS_INIT_SP_ADDR    (CONFIG_SYS_SDRAM_BASE + 0x1000 - \
                GENERATED_GBL_DATA_SIZE)

#define CONFIG_BOARD_EARLY_INIT_F

#endif /* __CONFIG_H */

4.3  宏定义查找总结

我们在阅读源代码的时候,判断一个宏有没有定义,我们重点关注以下两个文件,具体可以参考2.4节分析:

  • include/generated/autoconf.h;
  • include/configs/smdk2410.h;

参考文章:

[1]U-BOOT-2016.07移植 (第一篇) 初步分析

[2]uboot启动 -- uboot基本启动流程

[3]从零开始之uboot、移植uboot2017.01(五、board_init_f分析)

[4]u-boot2020.04移植(4、board_init_f)

[5]U-boot源码阅读-使用u-boot.map定位函数位置

posted @ 2021-10-28 23:51  大奥特曼打小怪兽  阅读(943)  评论(0编辑  收藏  举报
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