linux kernel 1.0 网络模块代码分析——目录及Makefile

在linux kernel 1.0的net目录下查看子目录及文件结构：

[root@localhost net]# ls -R
.:
ddi.c inet Makefile  socket.c  Space.c  unix

./inet:
arp.c  datagram.c  dev.h  eth.h   icmp.h  ip.c  loopback.c  packet.c  protocol.c  raw.c  README   route.h   skbuff.h  sock.h  tcp.h    udp.c  utils.c
arp.h  dev.c       eth.c  icmp.c  inet.h  ip.h  Makefile    proc.c    protocol.h  raw.h  route.c  skbuff.c  sock.c    tcp.c   timer.c  udp.h

./unix:
Makefile  proc.c  sock.c  unix.h

可以看到net由ddi.c，socket.c和Space.c三个文件，inet和unix两个目录，还有Makefile组成。
暂时不理睬inet和unix目录下的文件，看看Makefile的内容：

# Note! Dependencies are done automagically by 'make dep', which also
# removes any old dependencies. DON'T put your own dependencies here
# unless it's something special (ie not a .c file).
#
# Note 2! The CFLAGS definition is now in the main makefile...

# only these two lines should need to be changed to remove inet sockets.
# (and the inet/tcpip.o in net.o)

SUBDIRS     := unix inet

SUBOBJS     := $(foreach f,$(SUBDIRS),$f/$f.o)
#SUBOBJS的值为 unix/unix.o inet/inet.o

.c.o:
$(CC) $(CFLAGS) -c $<
.s.o:
$(AS) -o $*.o $<
.c.s:
$(CC) $(CFLAGS) -S $<
#老式makefile中的隐式规则定义
#如果编译目标为xx.o:xx.c则自动引用第一个规则，依此类推

OBJS    =  Space.o ddi.o socket.o

all:            subdirs net.o

net.o:          $(OBJS) network.a
$(LD) -r -o net.o $(OBJS) network.a
#将Space.o,ddi.o,socket.o和netowrk.a编译成net.o，net.o再编译进内核中。

network.a:      $(SUBOBJS)
rm -f $@
ar rc $@ $(SUBOBJS)
ranlib $@
#将unix/unix.o和inet/inet.o打包成network.a

subdirs:        dummy
set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i; done
#进入各个子目录分别编译unix.o和inet.o

dep:
$(CPP) -M *.c > .depend
set -e; for i in $(SUBDIRS); do $(MAKE) -C $$i dep; done

dummy:
#假的target

#
# include a dependency file if one exists
#
ifeq (.depend,$(wildcard .depend))
include .depend
endif

"Makefile" 51L, 1023C

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