//-------------------------------------------------------------------
//	cr4.c
//
//	This module creates a pseudo-file (named '/proc/cr4') which
//	allows applications to obtain the current value held in the
//	processor's CR4 register.  Individual bits in this register
//	are set by the operating system to either enable or disable
//	special features of the Pentium's operations (including the
//	scheme by which the CPU translates virtual memory-addresses 
//	to physical memory-addresses).  Refer to Volume 3 of "IA-32
//	Intel Architecture Software Developer's Manual" (Chapter 2)
//	for detailed explanation of all bits in Control Register 4.
//
//	NOTE: Developed and tested with Linux kernel version 2.6.9.
//
//	programmer: ALLAN CRUSE
//	written on: 07 JAN 2005
//-------------------------------------------------------------------

#include <linux/module.h>	// for init_module() 
#include <linux/proc_fs.h>	// for create_proc_info_entry() 

static char modname[] = "cr4";
static int cr4;

static int my_get_info( char *buf, char **start, off_t off, int count )
{
	int	len = 0;
       
	asm(" movl %cr4, %ebx \n movl %ebx, cr4 ");

	len += sprintf( buf+len, "cr4=%08X  ", cr4 );
	len += sprintf( buf+len, "PSE=%X  ", (cr4>>4)&1 );
	len += sprintf( buf+len, "PAE=%X  ", (cr4>>5)&1 );
	len += sprintf( buf+len, "\n" );	
	return	len;
}


int init_module( void )
{
	printk( "<1>\nInstalling \'%s\' module\n", modname );
	create_proc_info_entry( modname, 0, NULL, my_get_info );
	return	0;  // SUCCESS
}


void cleanup_module( void )
{
	remove_proc_entry( modname, NULL );
	printk( "<1>Removing \'%s\' module\n", modname );
}

MODULE_LICENSE("GPL");