Hello ,

I am developing a feature in a X86-64 machine running kernel 3.5.5. I am exporting this symbol to test FPU and kernel compiles fine if I call this symbol from my module it works great. But when I used this symbol from scheduler particularly enqueue_fair() (few times per second) in/kernel/sched/fair.c it behaves weirdly. During boot kernel hangs abruptly after few hundreds correct prints in this function after 1st print. 

Am I missing any rule, because I looked it up on internet they says nothing else than this way to use fpu. Any help is appreciated. I tried 10-20 boots and each time it hangs.

  1 /*test FPU*/

  2 #include <asm/i387.h>

  3 #include <linux/time.h>

  4 

  5 

  6 void my_symbol(void){

  7     unsigned long i = get_seconds();

  8    

  9     printk(KERN_DEBUG "i:%lu,",i);

 10     kernel_fpu_begin();

 11             float d = 3.123456*(i%3);

 12             i=(unsigned long)(d*1000000);

 13     kernel_fpu_end();

 14     printk(KERN_DEBUG "%lu\n",i);

 15 }

 16 EXPORT_SYMBOL_GPL(my_symbol);

thanks