Makefile

# Makefile
# Declare Name of kernel module
KMOD = test

# Enumerate Source files for kernel module
SRCS = test.c
SRCS += device_if.h bus_if.h

i:
	sudo kldload ./test.ko
r:
	sudo kldunload ./test.ko


.include <bsd.kmod.mk>

test.c

/* test.c 
 * written by Tsuyoshi Ozawa
 * http://d.hatena.ne.jp/big-eyed-hamster */

/* including for "kldloading", "kldunloading"  */
#include <sys/param.h>
#include <sys/module.h>
#include <sys/kernel.h>
#include <sys/systm.h>
/* including for handling IRQ  */
#include <sys/bus.h>
#include <machine/resource.h> /*To use SYS_RES_IRQ*/
#include <sys/rman.h> /*To use RF_ACTIVE*/

#include <sys/callout.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/mutex.h>

#include <machine/pcpu.h>
#include <machine/frame.h>

extern int (*mycallback)(void);
extern int callwheelmask;
extern void (*tick_sched)(void);
extern void (*lapic_handler)(struct trapframe *frame);
extern void lapic_handle_timer(struct trapframe *frame);
extern void dynamic_lapic_handle_timer(struct trapframe *frame);
extern void __lapic_handle_timer(struct trapframe *frame);
extern int (*get_skip_cnt)(void);

extern u_long lapic_timer_period, lapic_timer_hz;

void lapic_timer_periodic(u_int count);
void lapic_timer_oneshot(u_int count);

int test_intr(void *v);

struct callout_cpu {
        struct mtx              cc_lock;
        struct callout          *cc_callout;
        struct callout_tailq    *cc_callwheel;
        struct callout_list     cc_callfree;
        struct callout          *cc_next;
        struct callout          *cc_curr;
        void                    *cc_cookie;
        int                     cc_softticks;
        int                     cc_cancel;
        int                     cc_waiting;
};

extern struct callout_cpu cc_cpu;
extern int callwheelsize;
extern void switch_to_dynticks(void);
extern void switch_to_perticks(void);

/* need for "kldloading", "kldunloading"  */
static int 
test_modevent( struct module *module, int event, void *args) 
{
        int e = 0;  

        switch (event) {
        case MOD_LOAD:
                uprintf("loaded.\n");
                switch_to_dynticks();
                break;
        case MOD_UNLOAD:
                uprintf("unloaded.\n");
                switch_to_perticks();
                break;
        default:
                e = EOPNOTSUPP;
        }   
        return (e);
}

static moduledata_t test_conf ={
        "test",
        test_modevent,
        NULL
};

DECLARE_MODULE(test, test_conf, SI_SUB_DRIVERS, SI_ORDER_MIDDLE);