一。 make menuconfig 開啟 Enable Enable loadable module support
 --------------------------------------------------------------------------------------------
  +----------------------------- Linux Kernel Configuration ------------------------------+
  |  Arrow keys navigate the menu.  <Enter> selects submenus --->.  Highlighted letters   |
  |  are hotkeys.  Pressing <Y> includes, <N> excludes, <M> modularizes features.  Press  |
  |  <Esc><Esc> to exit, <?> for Help, </> for Search.  Legend: [*] built-in  [ ]         |
  |  excluded  <M> module  < > module capable                                             |
  | +-----------------------------------------------------------------------------------+ |
  | |          General setup  --->                                                      | |
  | |      [*] Enable loadable module support  --->                                     | |
  | |      -*- Enable the block layer  --->                                             | |
  | |          Linux Kernel Study & Practice  --->                                      | |

   同時在下級選單使能模組解除安裝，否則解除安裝的時候會報錯 rmmod: delete_module 'hello' failed (errno 38)
  
   |      --- Enable loadable module support                                           | |
  | |      [ ]   Forced module loading                                                  | |
  | |      [*]   Module unloading                                                       | |
  | |      [ ]     Forced module unloading (NEW)                                        | |
  | |      [ ]   Module versioning support                                              | |
  | |      [ ]   Source checksum for all modules 
 
 二。把對應原始碼的config配置修改為模組方式
  Kconfig檔案：
  config HELLO
     tristate "First Android Driver"
     default n
     help
     This is the first android driver.
 
   menuconfig設為M ，模組方式
 +-----------------------------------------------------------------------------------+ |
  | |      --- kernel study start support                                               | |
  | |      <M>   First Android Driver    
 
   Makefile 檔案
   obj-$(CONFIG_HELLO) += hello.o

 三 編譯模組
  先 make
  再 make modules
   如果最後連線報錯，有些系統介面找不到，是應該依賴模組的obj檔案還沒有生成， 那就先make 一下再make modules
  
  四 載入模組
   使用adb工具 push 到 目標系統
   # adb remount                  /*解決只讀問題*/
   # adb push hello.ko /system/   /*推送模組到目標板*/
   # insmod /system/hello.ko      /*載入模組到核心*/
   # lsmod                        /*顯示已載入的模組*/ 
   #