From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH 10/10] x86, ACPI: default to reboot via ACPI (again) Date: Mon, 10 Nov 2008 09:39:38 +0100 Message-ID: <20081110083938.GD22392@elte.hu> References: <007e7d616a5d1c2e16ad627d03f8b97799445e71.1226032943.git.len.brown@intel.com> <200811080930.21462.arvidjaar@mail.ru> <200811081050.25477.arvidjaar@mail.ru> <20081108115956.GE8354@elte.hu> <4916B38B.7050905@redhat.com> <4916B4DB.90602@zytor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx2.mail.elte.hu ([157.181.151.9]:37854 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753909AbYKJIkB (ORCPT ); Mon, 10 Nov 2008 03:40:01 -0500 Content-Disposition: inline In-Reply-To: <4916B4DB.90602@zytor.com> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: "H. Peter Anvin" , "Eric W. Biederman" Cc: Avi Kivity , Andrey Borzenkov , Len Brown , linux-acpi@vger.kernel.org, Len Brown , Thomas Gleixner , Eduardo Habkost , Andrew Morton * H. Peter Anvin wrote: > Avi Kivity wrote: > > > > I think the sequence should be acpi -> kbd -> triple fault. Given that > > Windows uses ACPI, the number of machines that support it is much larger > > (and growing daily) than the number of machines that do not. > > > > Like with many other things ACPI, there probably should be an ACPI > date cutoff for using it by default. There is also port CF9 reboot > (often incorrectly described as "PCI reboot", but it has nothing to > do with the PCI standard.) so, the sequence should be: [ acpi if date > 2007 ] -> kbd -> triple fault Where in this sequence should we insert port-CF9 reboot? We have no discovery of it, etc. The KGDB reboot will do _something_ on most boxes, so inserting it like this: [ acpi if date > 2007 ] -> kbd -> port-CF9 -> triple fault ... will likely have no practical impact as we rarely get to the triple fault method to begin with. So the reboot chain we'd like to have is: [ acpi if date > 2007 ] -> safe-port-CF9 -> kbd -> triple fault ... where safe-port-CF9 is something that can be done safely on all x86 boxes. Anyway, safe-port-CF9 aside, the ACPI sequence should definitely be cutoff based, so the plain re-introduction of the patch that changes the default is not acceptable. Ingo