Linking kernel module with precompiled object

Question

Im trying to build and insert a kernel module that uses precompiled object file. The precompiled object file was compiled with asm (GNU assembler).

Here is the Makefile:

obj-m += klm.o
klm-objs := a.o
klm.o:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
clean:
        make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean

and klm.c:

#define LINUX

#include <linux/module.h>  
#include <linux/kernel.h>  
#include <linux/slab.h>
extern volatile unsigned long peak_create();
int init_module(void)
{
   printk("<1>Hello world 1.\n");
   peak_create(); 
   return 0;
}


void cleanup_module(void)
{
  printk(KERN_ALERT "Goodbye world 1.\n");
}  

EXPORT_SYMBOL_GPL(peak_create);
MODULE_LICENSE("GPL");

But when I’m trying to insert the ko file (using insmod klm.ko) dmesg shows the error:

klm: Unknown symbol peak_create (err 0)

the source file of a.o contains global deceleration of peak_create. (.globl peak_create)

How can I use peak_create in the kernel module ?

Thank you all!

Answer 1

Try modifying the Makefile to this :

obj-m := klm_out.o
klm_out-objs : klm.o a.o

modules:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules
    # Put the asm compilation command here

clean:
    make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
    rm -f a.o