2.7. Modules
Spanning Multiple Files
Sometimes it makes sense to divide a kernel module between
several source files.
Here's an example of such a kernel module.
Example 2-8. start.c
/*
* start.c - Illustration of multi filed modules
*/
#include <linux/kernel.h> /* We're doing kernel work */
#include <linux/module.h> /* Specifically, a module */
int init_module(void)
{
printk(KERN_INFO "Hello, world - this is the kernel speaking\n");
return 0;
}
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The next file:
Example 2-9. stop.c
/*
* stop.c - Illustration of multi filed modules
*/
#include <linux/kernel.h> /* We're doing kernel work */
#include <linux/module.h> /* Specifically, a module */
void cleanup_module()
{
printk(KERN_INFO "Short is the life of a kernel module\n");
}
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And finally, the makefile:
Example 2-10. Makefile
obj-m += hello-1.o
obj-m += hello-2.o
obj-m += hello-3.o
obj-m += hello-4.o
obj-m += hello-5.o
obj-m += startstop.o
startstop-objs := start.o stop.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
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This is the complete makefile for all the examples we've seen so
far. The first five lines are nothing special, but for the last
example we'll need two lines. First we invent an object name for
our combined module, second we tell make
what object files are part of that module.
