u-boot Kconfig结构解析

1

/u-boot-2019.07/Kconfig

source "arch/Kconfig"

2

/u-boot-2019.07/arch/Kconfig  -->有一个一个选项，可以选择ARM architecture

choice
    prompt "Architecture select"
    default SANDBOX

config ARM
    bool "ARM architecture"
    select CREATE_ARCH_SYMLINK
    select HAVE_PRIVATE_LIBGCC if !ARM64
    select SUPPORT_OF_CONTROL

source "arch/arm/Kconfig"

3

/u-boot-2019.07/arch/arm/Kconfig

menu "ARM architecture"
    depends on ARM           #依赖上一层选择了ARM

config SYS_ARCH
    default "arm"          #CONFIG_SYS_ARCH 默认 arm

config ARM64
    bool                        #bool没有设置，这时候依赖别的项来select bool有设置的可以手动选择
    select PHYS_64BIT
    select SYS_CACHE_SHIFT_6

choice　　　　　　　#在这里选machine
    prompt "Target select"
    default TARGET_HIKEY

#以mx6为例

config ARCH_MX6     #machine 有一个配置项可以选 这里选的只是MX6架构的，这个架构下可能还有很多类型板卡，接着看怎么处理的。
    bool "Freescale MX6"
    select CPU_V7A  
    select SYS_FSL_HAS_SEC if SECURE_BOOT
    select SYS_FSL_SEC_COMPAT_4
    select SYS_FSL_SEC_LE
    select SYS_THUMB_BUILD if SPL
    imply MXC_GPIO

config CPU_V7A #选择V7A需要再选择以下部分
    bool
    select HAS_VBAR
    select HAS_THUMB2
    select SYS_CACHE_SHIFT_6
    imply SYS_ARM_MMU

config SYS_CPU
    default "arm720t" if CPU_ARM720T
    default "arm920t" if CPU_ARM920T
    default "arm926ejs" if CPU_ARM926EJS
    default "arm946es" if CPU_ARM946ES
    default "arm1136" if CPU_ARM1136
    default "arm1176" if CPU_ARM1176
    default "armv7" if CPU_V7A    #在这里选了SYS_CPU
    default "armv7" if CPU_V7R
    default "armv7m" if CPU_V7M
    default "pxa" if CPU_PXA
    default "sa1100" if CPU_SA1100
    default "armv8" if ARM64

if ARCH_MX6
config SPL_LDSCRIPT
    default "arch/arm/mach-omap2/u-boot-spl.lds"
endif

config ARCH_OWL
    bool "Actions Semi OWL SoCs"
    select ARM64           #在这里选了ARM64，再通过ARM64去选别的
    select DM
    select DM_SERIAL
    select OF_CONTROL
    imply CMD_DM

source "arch/arm/mach-imx/Kconfig"  #整个imx的一些配置 根据选择的板子不同 反过来在这里配置一些通用的东西

source "arch/arm/mach-imx/mx6/Kconfig" #mx6的一些配置 在这里选板子board

#应该还有board的config 各家公司代码不同 source "board/freescale/mx6ullevk/Kconfig"

但我思考了一下，觉得Freescale的代码风格还不错，

arch/Kconfig 选ARCH arm 包含arch/arm/Kconfig

arch/arm/Kconfig 选machine 包含arch/arm/mach-imx/Kconfig 和 arch/arm/mach-imx/mx6/Kconfig

这是公司名称                                   这是machine

arch/arm/mach-imx/mx6/Kconfig 选board 包含board/freescale/mx6ullevk/Kconfig

4

/u-boot-2019.07/arch/arm/mach-imx/mx6/Kconfig

if ARCH_MX6
choice                                              #在这里选板子board
    prompt "MX6 board select"
    optional

config TARGET_MX6ULL_14X14_EVK
    bool "Support mx6ull_14x14_evk"
    select BOARD_LATE_INIT
    select DM
    select DM_THERMAL
    select MX6ULL
    imply CMD_DM

config SYS_SOC  #这里定义了SYS_SOC
    default "mx6"

source "board/freescale/mx6ullevk/Kconfig"

5

/u-boot-2019.07/board/freescale/mx6ullevk/Kconfig

if TARGET_MX6ULL_14X14_EVK

config SYS_BOARD
    default "mx6ullevk"

config SYS_VENDOR
    default "freescale"

config SYS_CONFIG_NAME
    default "mx6ullevk"

endif

总结一下：

1.就是在arch目录下的Kconfig中选了ARM

2.然后在arch/arm目录下的Kconfig中选了Machine（mach-xx），这个可以理解为soc，fmshql，如果以后有其他系列也可以列入 mach-zynq mach-zynqmp

3.在arch/arm/mach-xx目录下选中board，board目录下的Kconfig配置SYS_BOARD SYS_VENDOR等信息

doc/README.kconfig

Tips to add/remove boards
-------------------------

When adding a new board, the following steps are generally needed:

[1] Add a header file include/configs/<target>.h
 [2] Make sure to define necessary CONFIG_SYS_* in Kconfig:
       Define CONFIG_SYS_CPU="cpu" to compile arch/<arch>/cpu/<cpu>
       Define CONFIG_SYS_SOC="soc" to compile arch/<arch>/cpu/<cpu>/<soc>
       Define CONFIG_SYS_VENDOR="vendor" to compile board/<vendor>/common/*
         and board/<vendor>/<board>/*
       Define CONFIG_SYS_BOARD="board" to compile board/<board>/*
         (or board/<vendor>/<board>/* if CONFIG_SYS_VENDOR is defined)
       Define CONFIG_SYS_CONFIG_NAME="target" to include
         include/configs/<target>.h
 [3] Add a new entry to the board select menu in Kconfig.
     The board select menu is located in arch/<arch>/Kconfig or
     arch/<arch>/*/Kconfig.
 [4] Add a MAINTAINERS file
     It is generally placed at board/<board>/MAINTAINERS or
     board/<vendor>/<board>/MAINTAINERS
 [5] Add configs/<target>_defconfig

When removing an obsolete board, the following steps are generally needed:

[1] Remove configs/<target>_defconfig
 [2] Remove include/configs/<target>.h if it is not used by any other boards
 [3] Remove board/<vendor>/<board>/* or board/<board>/* if it is not used
     by any other boards
 [4] Update MAINTAINERS if necessary
 [5] Remove the unused entry from the board select menu in Kconfig
 [6] Add an entry to doc/README.scrapyard