From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752786Ab1HFPaW (ORCPT ); Sat, 6 Aug 2011 11:30:22 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:36020 "EHLO cavan.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751411Ab1HFPaV (ORCPT ); Sat, 6 Aug 2011 11:30:21 -0400 Date: Sat, 6 Aug 2011 16:30:03 +0100 From: Matthew Garrett To: Ingo Molnar Cc: Mel Gorman , tglx@linutronix.de, hpa@zytor.com, bruno@ioda-net.ch, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Add reboot quirk for Dell Precision M4600 Message-ID: <20110806153003.GA1238@srcf.ucam.org> References: <20110727125651.GH3010@suse.de> <20110806065635.GE13220@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110806065635.GE13220@elte.hu> User-Agent: Mutt/1.5.20 (2009-06-14) X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@cavan.codon.org.uk X-SA-Exim-Scanned: No (on cavan.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Aug 06, 2011 at 08:56:35AM +0200, Ingo Molnar wrote: > Weird - ACPI is the default Windows method of reboot - how come it > does not work on that box? Does Windows work around this specific > machine (unlikely), or is our ACPI boot sequence not 100% compatible > with the Windows method (more likely IMO)? The ACPI reboot method on these machines hits the keyboard controller rather than PCI, which is unusual. What I suspect is that the write triggers some SMM or EC code that's making assumptions about system state, and we're not quite identical. Bouncing on the keyboard controller from userspace with init=/bin/bash wedges in the same way. -- Matthew Garrett | mjg59@srcf.ucam.org