linux-kernel - writing to performance monitoring register

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Date:	Wed, 13 Dec 2006 06:08:02 +0000 (GMT)
From:	ranjith kumar <ranjit_kumar_b4u@...oo.co.uk>
To:	linux-kernel@...r.kernel.org
Subject: writing to performance monitoring register

Hi,
    I want to measure number of last level cache
misses in Pentium 4 processor. In IA-32 programmers
manuals it was given that there are (architectural=
same across all IA-32 processors)perfomance monitoring
counters starting at address   0c1H and
performance_event_select registers starting at address
186H. 

1) When I tried to run a kernel module to write some
value in performance event select register (with
address 186H) by wrmsr instruction, the system is
hanging.Why?
The program is :
#include <linux/module.h> /* Needed by all modules */
#include <linux/kernel.h> /* Needed for KERN_INFO */
//#include<xmmintrin.h>
int i,j,k=0;
unsigned int xx,yy,xx1,yy1,xx2,yy2;
unsigned int t1,t2,t3,t4,BIG=0xffffffff;
int init_module(void)
{

asm volatile (" movl $0x186, %%ecx;"
	      " movl $0x0,   %%edx;"
	      " movl $0x0009412E, %%eax;"
	      " wrmsr;"
		:
		:
		:"%eax","%edx","%ecx"); 

printk(KERN_INFO " Initially %u=t1 %u=t2 %u=t3 %u=t4
\n",t1,t2,t3,t4);
 return 0;
}

void cleanup_module(void)
{
printk(KERN_INFO "Goodbye world \n");
}
-------------------------------------------------------
 2) Why I am getting compilation errors when I tried
to include <xmmintrin.h> or <stdio.h> ....files?

Thanks in advane.

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