From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Thu, 3 May 2001 15:10:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Thu, 3 May 2001 15:10:00 -0400 Received: from cisco7500-mainGW.gts.cz ([194.213.32.131]:2820 "EHLO bug.ucw.cz") by vger.kernel.org with ESMTP id ; Thu, 3 May 2001 15:09:50 -0400 Message-ID: <20010503210904.B9715@bug.ucw.cz> Date: Thu, 3 May 2001 21:09:04 +0200 From: Pavel Machek To: Helge Hafting , linux-kernel@vger.kernel.org Subject: Re: X15 alpha release: as fast as TUX but in user space (fwd) In-Reply-To: <20010428215301.A1052@gruyere.muc.suse.de> <200104282256.f3SMuRW15999@vindaloo.ras.ucalgary.ca> <9cg7t7$gbt$1@cesium.transmeta.com> <20010430104231.C3294@bug.ucw.cz> <3AF14DC5.17E35108@idb.hist.no> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93i In-Reply-To: <3AF14DC5.17E35108@idb.hist.no>; from Helge Hafting on Thu, May 03, 2001 at 02:23:33PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi! > > > > Whatever happened to that hack that was discussed a year or two ago? > > > > The one where (also on IA32) a magic page was set up by the kernel > > > > containing code for fast system calls, and the kernel would write > > > > calibation information to that magic page. The code written there > > > > would use the TSC in conjunction with that calibration data. > > > Pavel > > PS: Hmm, how do you do timewarp for just one userland appliation with > > this installed? > > 1. Kernel solution: give that particular process a different magic page > 2. User solution: Don't obtain time from the magic page. > 2a By changing program source, if available > 2b By switching the c library, assuming it is used That means that for fooling closed-source statically-linked binary, you now need to patch kernel. That's regression; subterfugue.org could do this with normal user rights in 2.4.0. -- I'm pavel@ucw.cz. "In my country we have almost anarchy and I don't care." Panos Katsaloulis describing me w.r.t. patents at discuss@linmodems.org