/****************************************************************************

 *                     I.MX6 U-Boot mkconfig hacking

 * 声明：

 *     本文主要是为了知道U-Boot中的mkconfig是如何工作的，是如何将配置

 * 中的内容进行汇总，同时又将这些内容放在了什么地方。

 *

 *                                       2015-12-19 深圳 南山区平山村 曾剑锋

 ***************************************************************************/

                    \\\\\\\\\-*- 目录 -*-//////////

                    |  一、参考文档：

                    |  二、Makefile

                    |  三、mkconfig

                    |  四、include/config.h

                    |  五、include/config.mk

                    ------------------------------

一、参考文档：

    . $(@:_config=)什么意思？

        http://blog.csdn.net/zbffff/article/details/18991145

    . U-BOOT Makefile注释

        http://wenku.baidu.com/view/ff14f319227916888486d7cb.html

    . makefile中的@

        http://www.cnblogs.com/lihaiping/archive/2013/03/20/makefile.html

    . Makefile中常用的函数

        http://linux.chinaunix.net/techdoc/develop/2009/07/09/1122854.shtml

    . U-Boot移植（二）——U-Boot编译过程分析（）

        http://blog.csdn.net/wafx1314/article/details/11260041

    . 请教linux make make clean make all 的具体用法

        http://zhidao.baidu.com/question/129692720.html

二、Makefile

    ......

    SRCTREE    := $(CURDIR)

    ......

    MKCONFIG   := $(SRCTREE)/mkconfig

    export MKCONFIG

    ......

    mx6solo_sabresd_config            \

    mx6solo_sabresd_mfg_config        \

    mx6solo_sabresd_android_config        \

    mx6dl_sabresd_config            \

    mx6dl_sabresd_mfg_config        \

    mx6dl_sabresd_android_config            \

    mx6q_sabresd_config            \

    mx6q_sabresd_android_config             \

    mx6q_sabresd_mfg_config            \

    mx6q_sabresd_iram_config    : unconfig

        @[ -z "$(findstring iram_,$@)" ] || \

            { echo "TEXT_BASE = 0x00907000" >$(obj)board/freescale/mx6q_sabresd/config.tmp ; \

              echo "... with iram configuration" ; \

            }

        @$(MKCONFIG) $(@:_config=) arm arm_cortexa8 mx6q_sabresd freescale mx6

    ......

三、mkconfig

    #!/bin/sh -e

    # Script to create header files and links to configure

    # U-Boot for a specific board.

    #

    # Parameters:  Target  Architecture  CPU  Board [VENDOR] [SOC]

    #

    # (C) - DENX Software Engineering, Wolfgang Denk <wd@denx.de>

    #

    APPEND=no    # Default: Create new config file

    # 开发板的名字

    BOARD_NAME=""    # Name to print in make output

    # 使用while循环和case进行命令行参数提取，很不错的处理方式

    while [ $# -gt  ] ; do

        case "$1" in

        --) shift ; break ;;

        -a) shift ; APPEND=yes ;;

        -n) shift ; BOARD_NAME="${1%%_config}" ; shift ;;   # %%去除$1字符串中的_config

        *)  break ;;

        esac

    done

    # 如果上面的命令行参数都没有，那么$1就是开发板的名字

    [ "${BOARD_NAME}" ] || BOARD_NAME="$1"

    # 参数个数小于4个或者大于6个，直接退出，比较奇怪的是，为什么不放在前面进行判断呢

    [ $# -lt  ] && exit

    [ $# -gt  ] && exit 

    # 显示提示信息

    echo "Configuring for ${BOARD_NAME} board..."

    #

    # Create link to architecture specific headers

    #

    # 如果编译出来的目录和源代码目录不一样，那么执行以下内容

    if [ "$SRCTREE" != "$OBJTREE" ] ; then

        mkdir -p ${OBJTREE}/include         # 创建include目录

        mkdir -p ${OBJTREE}/include2        # 创建include2目录

        cd ${OBJTREE}/include2              # 进入include2目录

        rm -f asm                           # 防止asm已经存在

        ln -s ${SRCTREE}/include/asm-$ asm # 重新软链接到固定的位置$(arm)平台

        LNPREFIX="../../include2/asm/"

        cd ../include

        rm -rf asm-$

        rm -f asm

        mkdir asm-$

        ln -s asm-$ asm

    else

        cd ./include

        rm -f asm

        ln -s asm-$ asm        # $=arm

    fi

    # 删除include/asm-arm/arch这个软链接

    rm -f asm-$/arch

    # $6等于mx6

    if [ -z "$6" -o "$6" = "NULL" ] ; then

        ln -s ${LNPREFIX}arch-$ asm-$/arch

    else

        ln -s ${LNPREFIX}arch-$ asm-$/arch

    fi

    if [ "$2" = "arm" ] ; then

        rm -f asm-$/proc

        ln -s ${LNPREFIX}proc-armv asm-$/proc

    fi

    #

    # Create include file for Make

    #

    echo "ARCH   = $2" >  config.mk     # $=arm

    echo "CPU    = $3" >> config.mk     # $=arm_cortexa8

    echo "BOARD  = $4" >> config.mk     # $=mx6q_sabresd

    # $=freescale

    [ "$5" ] && [ "$5" != "NULL" ] && echo "VENDOR = $5" >> config.mk

    # $=mx6

    [ "$6" ] && [ "$6" != "NULL" ] && echo "SOC    = $6" >> config.mk

    #

    # Create board specific header file

    # APPEND=no

    if [ "$APPEND" = "yes" ]    # Append to existing config file

    then

        echo >> config.h

    else

        > config.h        # Create new config file

    fi

    # 原来我们可以在在这个文件里查看config文件

    echo "/* Automatically generated - do not edit */" >>config.h

    # $=mx6dl_sabresd_android

    echo "#include <configs/$1.h>" >>config.h

    echo "#include <asm/config.h>" >>config.h

    exit 

四、include/config.h

    /* Automatically generated - do not edit */

    #include <configs/mx6dl_sabresd_android.h>

    #include <asm/config.h>

五、include/config.mk

    ARCH   = arm

    CPU    = arm_cortexa8

    BOARD  = mx6q_sabresd

    VENDOR = freescale

    SOC    = mx6

六、总结：

    从上面的情况可知，如果要在board目录下新建一个开发板<board_name>目录，则在include/configs目录下也要建立一个对应的<board_name>文件，里面存放的就是开发板<board_name>的配置信息。这里目前没有验证。