Hi,
I am writing a kernel module that calls rt_task_add_hook() to add a hook
when context switch occurs. I built a kernel module called
*switch_hook.ko*, but when I /insmod switch_hook.ko/, it complains
"*switch_hook: Unknown symbol rt_task_add_hook (err 0)*". I think I
missed something during the build process (failed to include Xenomai
source?) but I do not how to fix it. Below is my system settings, any
help is greatly appreciated.
*Patched Linux kernel source* is at "/usr/src/linux-3.5.7"
*Xenomai source* is at "/usr/src/xenomai-2.6.2.1"
*Xenomai libraries and binaries* is at "/usr/xenomai"
*My kernel module source code* is at **"/home/tomz/switch_hook_mod/",
and under this folder there are only two files: *Makefile* and
*switch_hook.c*. Here is how I make this module, and Makefile and
switch_hook.c's contents are attached as well:
/home/tomz/switch_hook_mod# *make EXTRA_CFLAGS="-I/usr/xenomai/include
-D_GNU_SOURCE -D_REENTRANT -D__XENO" EXTRA_LDFLAGS="-lnative
-L/usr/xenomai/lib -lxenomai -lpthread -lrt -lxenomai -lnative"*
*Makefile's content*
obj-m += switch_hook.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
*switch_hook.c's content*
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
#include <linux/init.h> /* Needed for the macros */
#include <native/task.h>
#include <native/timer.h>
#include <rtdk.h>
void hook_func(void *cookie){
printk(KERN_INFO "Context switch occured\n");
}
static int __init switch_hook_init(void)
{
rt_print_auto_init(1);
rt_printf("Add hook\n");
rt_task_add_hook(T_HOOK_SWITCH, &hook_func);
return 0;
}
static void __exit switch_hook_exit(void)
{
printk(KERN_INFO "Goodbye\n");
}
module_init(switch_hook_init);
module_exit(switch_hook_exit);
//end of switch_hook.c
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