regarding privilege levels of pentium 4

[Tim Prince]

Artūras Moskvinas wrote:
>> --- Sven Eschenberg <eschenb@cs.uni-frankfurt.de>
>> wrote:
>>

>> The OS I am using       : Linux.
>> The language in which the program is written : C(I am
>> attaching the program)
>> The compiler : gcc 3.2.3
>> Processor   : Pentium 4
>> I know password for root login. I logged in as root
>> and compiled my program. When compiled no errors were
>> reported. But when I run the program it simply shows
>> "Segmentation fault". 
>>
>> My goal is to measure performance parameters (for
>> example the number of branch instructions that were
>> mispredicted), on Pentium 4, using "RDMSR" and "WRMSR"
>> instructions. Also I want to disble interrupts while
>> running my program.
>> The problem is that those instructions can be run only
>> at privilege level zero.
> You should consider using Kernel mode linux (kernel recompilation
> needed) or write kernel module:
> kernel mode linux:
> http://web.yl.is.s.u-tokyo.ac.jp/~tosh/kml/
> 

Also, consider whether you need to re-invent the wheel, when both open 
and closed source profilers exist for this purpose.