AS              = $(CROSS_COMPILE)as  
LD              = $(CROSS_COMPILE)ld
REAL_CC         = $(CROSS_COMPILE)gcc
CPP             = $(CC) -E
AR              = $(CROSS_COMPILE)ar
NM              = $(CROSS_COMPILE)nm
STRIP           = $(CROSS_COMPILE)strip
OBJCOPY         = $(CROSS_COMPILE)objcopy
OBJDUMP         = $(CROSS_COMPILE)objdump

make ARCH=arm CROSS_COMPILE=arm-linux-

ARCH                                        ?=  $  (SUBARCH)
CROSS_COMPILE                               ?=

ARCH                                        ?=  arm
CROSS_COMPILE                               ?= arn-linux-

make ARCH=arm CROSS_COMPILE=arm-linux- xxx_defconfig

make help

make menuconfig

make zImage

make modules

CONFIG_XXX=y   # 对应的文件被编进内核
CONFIG_XXX=m   # 对应的文件被编成模块
#CONFIG_XXX   # 对应的文件没有被使用

config TINY4412_LEDS #配置选项的名称
        tristate "LED Support for FriendlyARM Tiny4412 GPIO LEDs"
       #tristate是变量类型有5种
       #Bool  布尔类型，结果是Y[*] ,  N[]
       #tristate 三项选择，结果是Y[*], N[], M[m]
       #String  字符串， 结果（arm-linux-）
       #Hex   十六进制
       #Int   十进制
        depends on MACH_TINY4412 #依赖
        #当依赖满足事，当前配置选项的提示信息才会出现，才能设置当前配置选项
        #如果依赖条件不满足，则它取默认值。
        default y #默认为y
        help #帮助信息
          This option enables support for LEDs connected to GPIO lines
          on Tiny4412 boards.

“menu” <prompt>
<menu options>
<menu block>
"endmenu"

“source” <prompt>

menu "Device Drivers"  #菜单开始
source "drivers/tty/Kconfig" #引入drivers/tty目录下的Kconfig
......
config TINY4412_LEDS
        tristate "LED Support for FriendlyARM Tiny4412 GPIO LEDs"
        depends on MACH_TINY4412
        default y
        help
          This option enables support for LEDs connected to GPIO lines
          on Tiny4412 boards.
......
endmenu#菜单结束

“choice”
<choice options>
<choice block>
"end choice"

choice
    prompt "Kernel compression mode"
    default KERNEL_GZIP
    depends on HAVE_KERNEL_GZIP || HAVE_KERNEL_BZIP2 || HAVE_KERNEL_LZMA || HAVE_KERNEL_XZ || HAVE_KERNEL_LZO
    help
      The linux kernel is a kind of self-extracting executable.
      Several compression algorithms are available, which differ
      in efficiency, compression and decompression speed.
      Compression speed is only relevant when building a kernel.
      Decompression speed is relevant at each boot.
      If you have any problems with bzip2 or lzma compressed
      kernels, mail me (Alain Knaff) <alain@knaff.lu>. (An older
      version of this functionality (bzip2 only), for 2.4, was
      supplied by Christian Ludwig)
      High compression options are mostly useful for users, who
      are low on disk space (embedded systems), but for whom ram
      size matters less.
      If in doubt, select ‘gzip‘
config KERNEL_GZIP
    bool "Gzip"
    depends on HAVE_KERNEL_GZIP
    help
      The old and tried gzip compression. It provides a good balance
      between compression ratio and decompression speed.
config KERNEL_BZIP2
    bool "Bzip2"
    depends on HAVE_KERNEL_BZIP2
    help
      Its compression ratio and speed is intermediate.
      Decompression speed is slowest among the choices.  The kernel
      size is about 10% smaller with bzip2, in comparison to gzip.
      Bzip2 uses a large amount of memory. For modern kernels you
      will need at least 8MB RAM or more for booting.
config KERNEL_LZMA
    bool "LZMA"
    depends on HAVE_KERNEL_LZMA
    help
      This compression algorithm‘s ratio is best.  Decompression speed
      is between gzip and bzip2.  Compression is slowest.
      The kernel size is about 33% smaller with LZMA in comparison to gzip.
config KERNEL_XZ
    bool "XZ"
    depends on HAVE_KERNEL_XZ
    help
      XZ uses the LZMA2 algorithm and instruction set specific
      BCJ filters which can improve compression ratio of executable
      code. The size of the kernel is about 30% smaller with XZ in
      comparison to gzip. On architectures for which there is a BCJ
      filter (i386, x86_64, ARM, IA-64, PowerPC, and SPARC), XZ
      will create a few percent smaller kernel than plain LZMA.
      The speed is about the same as with LZMA: The decompression
      speed of XZ is better than that of bzip2 but worse than gzip
      and LZO. Compression is slow.
config KERNEL_LZO
    bool "LZO"
    depends on HAVE_KERNEL_LZO
    help
      Its compression ratio is the poorest among the choices. The kernel
      size is about 10% bigger than gzip; however its speed
      (both compression and decompression) is the fastest.
endchoice

core-y          += kernel/ mm/ fs/ ipc/ security/ crypto/ block/
 # Objects we will link into vmlinux / subdirs we need to visit
init-y          := init/  
drivers-y       := drivers/ sound/ firmware/
net-y           := net/ 
libs-y          := lib/ 
core-y          := usr/ 

include $(srctree)/arch/$(SRCARCH)/Makefile

#对应arch/arm/kernel/head.o
head-y        := arch/arm/kernel/head$(MMUEXT).o 
......
core-$(CONFIG_FPE_NWFPE)    += arch/arm/nwfpe/
core-$(CONFIG_FPE_FASTFPE)    += $(FASTFPE_OBJ)
core-$(CONFIG_VFP)        += arch/arm/vfp/
# If we have a machine-specific directory, then include it in the build.
core-y                += arch/arm/kernel/ arch/arm/mm/ arch/arm/common/
core-y                += arch/arm/net/
core-y                += $(machdirs) $(platdirs)
drivers-$(CONFIG_OPROFILE)      += arch/arm/oprofile/
libs-y                := arch/arm/lib/ $(libs-y)

#linux-3.5/drivers/char/Makefile
obj-$(CONFIG_TINY4412_LEDS)     += tiny4412_leds.o
obj-$(CONFIG_TINY4412_HELLO_MODULE)     += tiny4412_hello_module.o
obj-$(CONFIG_TINY4412_BUTTONS)  += tiny4412_buttons.o
obj-$(CONFIG_TINY4412_BUZZER)   += tiny4412_pwm.o
obj-$(CONFIG_TINY4412_BACKLIGHT)+= tiny4412_backlight.o
obj-$(CONFIG_TINY4412_ADC)              += tiny4412_adc.o