From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754407AbYJNVFU (ORCPT ); Tue, 14 Oct 2008 17:05:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754990AbYJNVEw (ORCPT ); Tue, 14 Oct 2008 17:04:52 -0400 Received: from mx2.redhat.com ([66.187.237.31]:39196 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754790AbYJNVEv (ORCPT ); Tue, 14 Oct 2008 17:04:51 -0400 Date: Tue, 14 Oct 2008 23:04:04 +0200 From: Karel Zak To: Arjan van de Ven Cc: Linus Torvalds , Andrew Morton , Linux Kernel Mailing List , Nick Piggin , Ingo Molnar Subject: Re: [kerneloops] regression in 2.6.27 wrt "lock_page" and the "hwclock" program Message-ID: <20081014210404.GJ10429@nb.net.home> References: <20081004174433.14a5e093@infradead.org> <20081004215225.2444d54b.akpm@linux-foundation.org> <20081005081145.30ba921b@infradead.org> <20081005102742.de8353b4.akpm@linux-foundation.org> <20081005103826.6771540a@infradead.org> <20081012200004.GI10429@nb.net.home> <20081013105559.15ccb67f@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20081013105559.15ccb67f@infradead.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 13, 2008 at 10:55:59AM -0400, Arjan van de Ven wrote: > Karel: Can you describe what it WANTS to do so we can see if we can It wants to "atomically" (without context switch) read/write time from CMOS. This is unrealistic of course. > just extend the linux kernel to do that the right way? The kernel is already extended and hwclock uses the extension :-) The solution is /dev/rtc. The code that directly works with CMOS is fallback solution for people who don't want or can not use the standard RTC device. I guess people use this functionally for experiments only. Today the RTC framework should work everywhere. I'll simply remove the "cli" / "sti" code -- eventually I can try to optimize it by mlockall() and SCHED_FIFO (as suggested by Linus). Karel -- Karel Zak