Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759616AbYA0MmG (ORCPT ); Sun, 27 Jan 2008 07:42:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1760029AbYA0Mlf (ORCPT ); Sun, 27 Jan 2008 07:41:35 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:42751 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759995AbYA0Mlc (ORCPT ); Sun, 27 Jan 2008 07:41:32 -0500 Date: Sun, 27 Jan 2008 13:41:20 +0100 From: Ingo Molnar To: Kevin Winchester Cc: Thomas Gleixner , "H. Peter Anvin" , Linux Kernel Mailing List , John Stultz Subject: Re: X fails to start with latest Linus git Message-ID: <20080127124120.GA23377@elte.hu> References: <479BCE03.6070603@gmail.com> <479BD1D1.8020503@gmail.com> <20080127062703.GA23444@elte.hu> <20080127083129.c14452ca.kjwinchester@gmail.com> <20080127123702.GB21282@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080127123702.GB21282@elte.hu> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1560 Lines: 49 * Ingo Molnar wrote: > it seems you've got hpet active by default: > > /sys/devices/system/clocksource/clocksource0/current_clocksource: > hpet > /sys/devices/system/clocksource/clocksource0/available_clocksource: > hpet acpi_pm pit jiffies tsc btw., it's quite mysterious how this can lock up. ktime_get() on a hpet clocksource does a very straightforward: static cycle_t read_hpet(void) { return (cycle_t)hpet_readl(HPET_COUNTER); } which is a very simple thing: c0119470 : c0119470: 8b 15 b8 b4 ae c0 mov 0xc0aeb4b8,%edx c0119476: 55 push %ebp c0119477: 89 e5 mov %esp,%ebp c0119479: 5d pop %ebp c011947a: 01 d0 add %edx,%eax c011947c: 8b 00 mov (%eax),%eax c011947e: c3 ret basically just a memory access to an ioremap()-ed area. hm, perhaps it's due to the xtime lock dependency: do { seq = read_seqbegin(&xtime_lock); getnstimeofday(ts); tomono = wall_to_monotonic; } while (read_seqretry(&xtime_lock, seq)); perhaps your system somehow generates a printk from within an xtime_lock locked section? Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/