MODPOST 0 modules的解决办法

http://blog.163.com/luffy_ye/blog/static/12387653201061542917464/(转)

[root@localhost]~/kernel-stu/hello-1# make             

make -C /lib/modules/2.6.23.1-42.fc8/build M=/root/kernel-stu/hello-1 modules
make[1]: Entering directory `/usr/src/kernels/2.6.23.1-42.fc8-i686'
Building modules, stage 2.
MODPOST 0 modules
make[1]: Leaving directory `/usr/src/kernels/2.6.23.1-42.fc8-i686'

Solution: review the Makefile of the source code, any of the following can get this error:
First:
[root@localhost]~/kernel-stu/hello-1# cat Makefile
bj-m += hello-1.o
all:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
Second:
[root@localhost]~/kernel-stu/hello-1# cat Makefile
obj-m += hello-1.c
all:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

The right content of Makefile is:
[root@localhost]~/kernel-stu/hello-1# cat Makefile
obj-m += hello-1.o
all:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

The content of hello-1.c:
[root@localhost]~/kernel-stu/hello-1# cat hello-1.c

#include <linux/init.h>
#include <linux/module.h>
MODULE_LICENSE("Dual BSD/GPL");

static int hello_init(void){
        printk(KERN_ALERT "hello,world\n");
        return 0;
}

static void hello_exit(void){
        printk(KERN_ALERT "goodbye,cruel world\n");
      return 0;
      }

module_init(hello_init);
module_exit(hello_exit);

Make:
[root@localhost]~/kernel-stu/hello-1# make
make -C /lib/modules/2.6.23.1-42.fc8/build M=/root/kernel-stu/hello-1 modules
make[1]: Entering directory `/usr/src/kernels/2.6.23.1-42.fc8-i686'
CC [M] /root/kernel-stu/hello-1/hello-1.o
/root/kernel-stu/hello-1/hello-1.c: In function ‘hello_exit’:
/root/kernel-stu/hello-1/hello-1.c:13: warning: ‘return’ with a value, in function returning void
Building modules, stage 2.
MODPOST 1 modules
CC      /root/kernel-stu/hello-1/hello-1.mod.o
LD [M] /root/kernel-stu/hello-1/hello-1.ko
make[1]: Leaving directory `/usr/src/kernels/2.6.23.1-42.fc8-i686'

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

the kernel build system (kbuild) allows to compile modules whose sourceslive outside the kernel source tree by setting SUBDIRS as follows (fromthe module sources's directory):  $ make -C /lib/modules/$(uname -r)/build modules SUBDIRS=$(pwd)people use this mechanism to compile kernel modules that are missing intheir kernel sources, or have been updated/fixed in the meantime.Currently there are a number of deficiencies for building such modules:  (1) symbol versioning (MODVERSIONS) is not properly supported, and  (2) only the `modules' make target is supported.Problem (1) did not exist in the 2.4 kernel series. The currentsituation has lead authors of several external modules to implement someof the kbuild functionality in their own makefiles, which can only leadto problems later on.During the kernel compile, a list of all files that export symbols iscreated in .tmp_versions/ of the kernel source tree. After everything iscompiled, the module versions of all these object files are resolvedwith modpost. When an external module is compiled, it ends up being theonly file in .tmp_versions/, and so symbols in other modules would notbe found.An additional problem is that resolving symbol versions requires allmodule files plus vmlinux to be in the kernel source tree, so modulescannot be build against a clean kernel source tree.

Reference :

lwn.net/Articles/69148/

附：

obj-m 写为obj-s,也会报同样的错误；