Linux下一个ko模块中函数调用另一个ko模块中函数

mod_a.c

// Module A (mod_a.c)
#include
#include
#include
 
static int func1(void)
{
       printk("In Func: %s...\n",__func__);
       return 0;
}
 
// Export symbol func1
EXPORT_SYMBOL(func1);
 
static int __init hello_init(void)
{
       printk("Module 1,Init!\n");
       return 0;
}
 
static void __exit hello_exit(void)
{
       printk("Module 1,Exit!\n");
}
 
module_init(hello_init);
module_exit(hello_exit);

对应的makefile

ifneq ($(KERNELRELEASE),)
	obj-m := mod_a.o 
# Otherwise we were called directly from the command
# line; invoke the kernel build system.
else
	KERNELDIR ?= /lib/modules/$(shell uname -r)/build
	PWD := $(shell pwd) 
default:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
	 rm -rf *.o *.mod.c *.mod.o *.ko
 
endif

mod_b.c

// Module B (mod_b.c)
#include
#include
#include
 
static int func2(void)
{
       extern int func1(void);
       func1();
       printk("In Func: %s...\n",__func__);
       return 0;
}
 
static int __init hello_init(void)
{
       printk("Module 2,Init!\n");
       func2();
       return 0;
}
 
static void __exit hello_exit(void)
{
       printk("Module 2,Exit!\n");
}
 
module_init(hello_init);
module_exit(hello_exit);

对应的makefile

KBUILD_EXTRA_SYMBOLS += /mnt/hgfs/share/2020/kernel/moduleA/Module.symvers
export KBUILD_EXTRA_SYMBOLS
ifneq ($(KERNELRELEASE),)
	obj-m := mod_b.o 
# Otherwise we were called directly from the command
# line; invoke the kernel build system.
else
	KERNELDIR ?= /lib/modules/$(shell uname -r)/build
	PWD := $(shell pwd) 
default:
	$(MAKE) -C $(KERNELDIR) M=$(PWD) modules
clean:
	 rm -rf *.o *.mod.c *.mod.o *.ko *.symvers
 
endif

第二个makefiel的KBUILD_EXTRA_SYMBOLS是绝对路径