VERSION = 2
PATCHLEVEL = 0
SUBLEVEL = 1

ARCH = i386

#
# For SMP kernels, set this. We don't want to have this in the config file
# because it makes re-config very ugly and too many fundamental files depend
# on "CONFIG_SMP"
#
# NOTE! SMP is experimental. See the file Documentation/SMP.txt
#
# SMP = 1
#
# SMP profiling options
# SMP_PROF = 1

.EXPORT_ALL_VARIABLES:

CONFIG_SHELL := $(shell if [ -x "$$BASH" ]; then echo $$BASH; \
      else if [ -x /bin/bash ]; then echo /bin/bash; \
      else echo sh; fi ; fi)
TOPDIR  := $(shell if [ "$$PWD" != "" ]; then echo $$PWD; else pwd; fi)

HPATH       = $(TOPDIR)/include

HOSTCC      =gcc -I$(HPATH)
HOSTCFLAGS  =

CROSS_COMPILE   =

AS  =$(CROSS_COMPILE)as
LD  =$(CROSS_COMPILE)ld
CC  =$(CROSS_COMPILE)gcc -D__KERNEL__ -I$(HPATH)
CPP=$(CC) -E
AR  =$(CROSS_COMPILE)ar
NM  =$(CROSS_COMPILE)nm
STRIP   =$(CROSS_COMPILE)strip
MAKE    =make
AWK=gawk

all:    do-it-all

#
# Make "config" the default target if there is no configuration file or
# "depend" the target if there is no top-level dependency information.
#
ifeq (.config,$(wildcard .config))
include .config
ifeq (.depend,$(wildcard .depend)) //.depend 在linux 中是隐藏的，(ls -a)
include .depend
do-it-all:  Version vmlinux
else
CONFIGURATION = depend
do-it-all:  depend
endif
else
CONFIGURATION = config
do-it-all:  config
endif

在我的文件夹中，没有depend，config 这个配置文件，那么就执行红色部分的，

但 CONFIGURATION = config  config 是什么意思，do—it—all 的依赖config

config ？？？？？
#
# ROOT_DEV specifies the default root-device when making the image.
# This can be eithr FLOPPY, CURRENT, /dev/xxxx or empty, in which case
# the default of FLOPPY is used by 'build'.
#

ROOT_DEV = CURRENT

#
# INSTALL_PATH specifies where to place the updated kernel and system map
# images.  Uncomment if you want to place them anywhere other than root.

#INSTALL_PATH=/boot

#
# If you want to preset the SVGA mode, uncomment the next line and
# set SVGA_MODE to whatever number you want.
# Set it to -DSVGA_MODE=NORMAL_VGA if you just want the EGA/VGA mode.
# The number is the same as you would ordinarily press at bootup.
#

SVGA_MODE=  -DSVGA_MODE=NORMAL_VGA

#
# standard CFLAGS
#

CFLAGS = -Wall -Wstrict-prototypes -O2 -fomit-frame-pointer -fno-strength-reduce

ifdef CONFIG_CPP
CFLAGS := $(CFLAGS) -x c++
endif

ifdef SMP
CFLAGS += -D__SMP__
AFLAGS += -D__SMP__

ifdef SMP_PROF
CFLAGS += -D__SMP_PROF__
AFLAGS += -D__SMP_PROF__
endif
endif

#
# if you want the ram-disk device, define this to be the
# size in blocks.
#

#RAMDISK = -DRAMDISK=512

# Include the make variables (CC, etc...)
#

ARCHIVES    =kernel/kernel.o mm/mm.o fs/fs.o ipc/ipc.o net/network.a
FILESYSTEMS=fs/filesystems.a
DRIVERS     =drivers/block/block.a \
         drivers/char/char.a
LIBS        =$(TOPDIR)/lib/lib.a
SUBDIRS     =kernel drivers mm fs net ipc lib

ifeq ($(CONFIG_ISDN),y)
DRIVERS := $(DRIVERS) drivers/isdn/isdn.a
endif

DRIVERS := $(DRIVERS) drivers/net/net.a

ifdef CONFIG_CD_NO_IDESCSI
DRIVERS := $(DRIVERS) drivers/cdrom/cdrom.a
endif

ifeq ($(CONFIG_SCSI),y)
DRIVERS := $(DRIVERS) drivers/scsi/scsi.a
endif

ifeq ($(CONFIG_SOUND),y)
DRIVERS := $(DRIVERS) drivers/sound/sound.a
endif

ifdef CONFIG_PCI
DRIVERS := $(DRIVERS) drivers/pci/pci.a
endif

ifdef CONFIG_SBUS
DRIVERS := $(DRIVERS) drivers/sbus/sbus.a
endif

include arch/$(ARCH)/Makefile

ifdef SMP

.S.s:
    $(CC) -D__ASSEMBLY__ $(AFLAGS) -traditional -E -o $*.s $<
.S.o:
    $(CC) -D__ASSEMBLY__ $(AFLAGS) -traditional -c -o $*.o $<

else

.S.s:
    $(CC) -D__ASSEMBLY__ -traditional -E -o $*.s $<
.S.o:
    $(CC) -D__ASSEMBLY__ -traditional -c -o $*.o $<

endif

Version: dummy
    @rm -f include/linux/compile.h

boot: vmlinux
    @$(MAKE) -C arch/$(ARCH)/boot

vmlinux: $(CONFIGURATION) init/main.o init/version.o linuxsubdirs
    $(LD) $(LINKFLAGS) $(HEAD) init/main.o init/version.o \
        $(ARCHIVES) \
        $(FILESYSTEMS) \
        $(DRIVERS) \
        $(LIBS) -o vmlinux
    $(NM) vmlinux | grep -v '\(compiled\)\|\(\.o$$\)\|\( a \)' | sort > System.map

symlinks:
    rm -f include/asm
    ( cd include ; ln -sf asm-$(ARCH) asm)

oldconfig: symlinks
    $(CONFIG_SHELL) scripts/Configure -d arch/$(ARCH)/config.in

xconfig: symlinks
    $(MAKE) -C scripts kconfig.tk
    wish -f scripts/kconfig.tk

menuconfig: include/linux/version.h symlinks
    $(MAKE) -C scripts/lxdialog all
    $(CONFIG_SHELL) scripts/Menuconfig arch/$(ARCH)/config.in

config: symlinks
    $(CONFIG_SHELL) scripts/Configure arch/$(ARCH)/config.in

linuxsubdirs: dummy
    set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i; done

$(TOPDIR)/include/linux/version.h: include/linux/version.h
$(TOPDIR)/include/linux/compile.h: include/linux/compile.h

newversion:
    @if [ ! -f .version ]; then \
        echo 1 > .version; \
    else \
        expr 0`cat .version` + 1 > .version; \
    fi

include/linux/compile.h: $(CONFIGURATION) include/linux/version.h newversion
    @if [ -f .name ]; then \
       echo \#define UTS_VERSION \"\#`cat .version`-`cat .name` `date`\"; \
     else \
       echo \#define UTS_VERSION \"\#`cat .version` `date`\";  \
     fi >> .ver
    @echo \#define LINUX_COMPILE_TIME \"`date +%T`\" >> .ver
    @echo \#define LINUX_COMPILE_BY \"`whoami`\" >> .ver
    @echo \#define LINUX_COMPILE_HOST \"`hostname`\" >> .ver
    @if [ -x /bin/dnsdomainname ]; then \
       echo \#define LINUX_COMPILE_DOMAIN \"`dnsdomainname`\"; \
     elif [ -x /bin/domainname ]; then \
       echo \#define LINUX_COMPILE_DOMAIN \"`domainname`\"; \
     else \
       echo \#define LINUX_COMPILE_DOMAIN ; \
     fi >> .ver
    @echo \#define LINUX_COMPILER \"`$(CC) -v 2>&1 | tail -1`\" >> .ver
    @mv -f .ver $@

include/linux/version.h: ./Makefile
    @echo \#define UTS_RELEASE \"$(VERSION).$(PATCHLEVEL).$(SUBLEVEL)\" > .ver
    @echo \#define LINUX_VERSION_CODE `expr $(VERSION) \\* 65536 + $(PATCHLEVEL) \\* 256 + $(SUBLEVEL)` >> .ver
    @mv -f .ver $@

init/version.o: init/version.c include/linux/compile.h
    $(CC) $(CFLAGS) -DUTS_MACHINE='"$(ARCH)"' -c -o init/version.o init/version.c

init/main.o: init/main.c
    $(CC) $(CFLAGS) $(PROFILING) -c -o $*.o $<

fs: dummy
    $(MAKE) linuxsubdirs SUBDIRS=fs

lib: dummy
    $(MAKE) linuxsubdirs SUBDIRS=lib

mm: dummy
    $(MAKE) linuxsubdirs SUBDIRS=mm

ipc: dummy
    $(MAKE) linuxsubdirs SUBDIRS=ipc

kernel: dummy
    $(MAKE) linuxsubdirs SUBDIRS=kernel

drivers: dummy
    $(MAKE) linuxsubdirs SUBDIRS=drivers

net: dummy
    $(MAKE) linuxsubdirs SUBDIRS=net

MODFLAGS = -DMODULE
ifdef CONFIG_MODULES
ifdef CONFIG_MODVERSIONS
MODFLAGS += -DMODVERSIONS -include $(HPATH)/linux/modversions.h
endif

modules: include/linux/version.h
    @set -e; \
    for i in $(SUBDIRS); \
    do $(MAKE) -C $$i CFLAGS="$(CFLAGS) $(MODFLAGS)" MAKING_MODULES=1 modules; \
    done

modules_install:
    @( \
    MODLIB=/lib/modules/$(VERSION).$(PATCHLEVEL).$(SUBLEVEL); \
    cd modules; \
    MODULES=""; \
    inst_mod() { These="`cat $$1`"; MODULES="$$MODULES $$These"; \
        mkdir -p $$MODLIB/$$2; cp -p $$These $$MODLIB/$$2; \
        echo Installing modules under $$MODLIB/$$2; \
    }; \
    \
    if [ -f BLOCK_MODULES ]; then inst_mod BLOCK_MODULES block; fi; \
    if [ -f NET_MODULES   ]; then inst_mod NET_MODULES   net;   fi; \
    if [ -f IPV4_MODULES  ]; then inst_mod IPV4_MODULES  ipv4;  fi; \
    if [ -f SCSI_MODULES  ]; then inst_mod SCSI_MODULES  scsi;  fi; \
    if [ -f FS_MODULES    ]; then inst_mod FS_MODULES    fs;    fi; \
    if [ -f CDROM_MODULES ]; then inst_mod CDROM_MODULES cdrom; fi; \
    \
    ls *.o > .allmods; \
    echo $$MODULES | tr ' ' '\n' | sort | comm -23 .allmods - > .misc; \
    if [ -s .misc ]; then inst_mod .misc misc; fi; \
    rm -f .misc .allmods; \
    )

# modules disabled....

else
modules modules_install: dummy
    @echo
    @echo "The present kernel configuration has modules disabled."
    @echo "Type 'make config' and enable loadable module support."
    @echo "Then build a kernel with module support enabled."
    @echo
    @exit 1
endif

clean:  archclean
    rm -f kernel/ksyms.lst include/linux/compile.h
    rm -f core `find . -name '*.[oas]' ! -regex '.*lxdialog/.*' -print`
    rm -f core `find . -type f -name 'core' -print`
    rm -f vmlinux System.map
    rm -f .tmp* drivers/sound/configure
    rm -fr modules/*
    rm -f submenu*

mrproper: clean
    rm -f include/linux/autoconf.h include/linux/version.h
    rm -f drivers/sound/local.h drivers/sound/.defines
    rm -f drivers/scsi/aic7xxx_asm drivers/scsi/aic7xxx_seq.h
    rm -f drivers/char/uni_hash.tbl drivers/char/conmakehash
    rm -f .version .config* config.in config.old
    rm -f scripts/tkparse scripts/kconfig.tk scripts/kconfig.tmp
    rm -f scripts/lxdialog/*.o scripts/lxdialog/lxdialog
    rm -f .menuconfig .menuconfig.log
    rm -f include/asm
    rm -f .depend `find . -name .depend -print`
    rm -f .hdepend
    rm -f $(TOPDIR)/include/linux/modversions.h
    rm -f $(TOPDIR)/include/linux/modules/*


distclean: mrproper
    rm -f core `find . \( -name '*.orig' -o -name '*.rej' -o -name '*~' \
                -o -name '*.bak' -o -name '#*#' -o -name '.*.orig' \
                -o -name '.*.rej' -o -name '.SUMS' -o -size 0 \) -print` TAGS

backup: mrproper
    cd .. && tar cf - linux/ | gzip -9 > backup.gz
    sync

sums:
    find . -type f -print | sort | xargs sum > .SUMS

dep-files: archdep .hdepend include/linux/version.h
    $(AWK) -f scripts/depend.awk init/*.c > .tmpdepend
    set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i fastdep; done
    mv .tmpdepend .depend

MODVERFILE :=

ifdef CONFIG_MODVERSIONS
MODVERFILE := $(TOPDIR)/include/linux/modversions.h
endif

depend dep: dep-files $(MODVERFILE)

ifdef CONFIGURATION
..$(CONFIGURATION):
    @echo
    @echo "You have a bad or nonexistent" .$(CONFIGURATION) ": running 'make" $(CONFIGURATION)"'"
    @echo
    $(MAKE) $(CONFIGURATION)
    @echo
    @echo "Successful. Try re-making (ignore the error that follows)"
    @echo
    exit 1

#dummy: ..$(CONFIGURATION)
dummy:

else

dummy:

endif

include Rules.make

#
# This generates dependencies for the .h files.
#

.hdepend: dummy
    rm -f $@
    $(AWK) -f scripts/depend.awk `find $(HPATH) -name \*.h ! -name modversions.h -print` > .$@
    mv .$@ $@