From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753065AbWKLUQp (ORCPT ); Sun, 12 Nov 2006 15:16:45 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753073AbWKLUQp (ORCPT ); Sun, 12 Nov 2006 15:16:45 -0500 Received: from fest.stud.feec.vutbr.cz ([147.229.72.16]:16592 "EHLO fest.stud.feec.vutbr.cz") by vger.kernel.org with ESMTP id S1753068AbWKLUQp (ORCPT ); Sun, 12 Nov 2006 15:16:45 -0500 Message-ID: <45578126.2000306@stud.feec.vutbr.cz> Date: Sun, 12 Nov 2006 21:16:38 +0100 From: Michal Schmidt User-Agent: Icedove 1.5.0.7 (X11/20061013) MIME-Version: 1.0 To: ranjith kumar CC: linux-kernel@vger.kernel.org Subject: Re: privilege level of program which is called by call_usermodehelper() References: <20061112190848.37896.qmail@web27401.mail.ukl.yahoo.com> In-Reply-To: <20061112190848.37896.qmail@web27401.mail.ukl.yahoo.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org ranjith kumar wrote: > Hi, > > I think the program which is called by > call_usermodehelper() will not be executed at > privilege level zero on IA-32 machines. > Am I right? Right. Only the kernel runs in privilege level (ring) 0. > How to run a program which has been compiled by a > compiler(say gcc) at privilege level zero? You don't. Well, you could put it in the kernel... > Indeed I want to compare time taken in executing two > programs. If we run them at privilege level zero by > calling them in a kernel module, processor will not > switch to other processors. That's a false assumption. Even kernel code is preemptible nowadays. > So that we can find out > time taken to execute a program more accurately. If you run your program on an otherwise idle machine, the results should be pretty accurate. If you really think it matters, then run your program with real-time priority. > What you say?? > Thanks in advance. Michal