regarding privilege levels of pentium 4

Artūras Moskvinas
Sat Sep 30 22:28:00 GMT 2006

> --- Sven Eschenberg <>
> wrote:
>> Hi Ranjith,
>> I might be wrong on this, but I think the question
>> is, if the Operating 
>> System permits it or under which circumstances. It's
>> neither a question 
>> of what gcc or the hardware does, but what the OS
>> you are using allows 
>> to which processes.
> Thanks. I am sending more details of my problem.
> 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:

Arturas M.

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