From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264665AbUEYEnJ (ORCPT ); Tue, 25 May 2004 00:43:09 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264637AbUEYEnJ (ORCPT ); Tue, 25 May 2004 00:43:09 -0400 Received: from palrel13.hp.com ([156.153.255.238]:20694 "EHLO palrel13.hp.com") by vger.kernel.org with ESMTP id S264643AbUEYEnF (ORCPT ); Tue, 25 May 2004 00:43:05 -0400 From: David Mosberger MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16562.52948.981913.814783@napali.hpl.hp.com> Date: Mon, 24 May 2004 21:43:00 -0700 To: Andrea Arcangeli Cc: Linus Torvalds , Benjamin Herrenschmidt , Andrew Morton , Linux Kernel list , Ingo Molnar , Ben LaHaise , linux-mm@kvack.org, Architectures Group Subject: Re: [PATCH] ppc64: Fix possible race with set_pte on a present PTE In-Reply-To: <20040525042054.GU29378@dualathlon.random> References: <1085369393.15315.28.camel@gaston> <1085371988.15281.38.camel@gaston> <1085373839.14969.42.camel@gaston> <20040525034326.GT29378@dualathlon.random> <20040525042054.GU29378@dualathlon.random> X-Mailer: VM 7.18 under Emacs 21.3.1 Reply-To: davidm@hpl.hp.com X-URL: http://www.hpl.hp.com/personal/David_Mosberger/ Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org >>>>> On Tue, 25 May 2004 06:20:54 +0200, Andrea Arcangeli said: Andrea> the only architecture that has the accessed bit in Andrea> _hardware_ via page faults I know is ia64, but I don't know Andrea> if it has a mode to set it without page faults No, it doesn't. Andrea> and how it is implementing the accessed bit in linux. If the "accessed" or "dirty" bits are zero, accessing/writing the page will cause a fault which will be handled in a low-level fault handler. The Linux version of these handlers simply turn on the respective bit. See daccess_bit(), iaccess_bit(), and dirty_bit() in arch/ia64/kernel/ivt.S. Note: I'm on travel and haven't seen the context of this discussion and don't expect to have time to think about this until I return on Thursday. So if you don't hear from me, it's not because I'm ignoring you... ;-) --david