From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: [PATCH 10/10] x86, ACPI: default to reboot via ACPI (again) Date: Mon, 10 Nov 2008 10:54:01 +0200 Message-ID: <4917F6A9.3020408@redhat.com> 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> <20081110083938.GD22392@elte.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from mx2.redhat.com ([66.187.237.31]:39648 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753478AbYKJIzI (ORCPT ); Mon, 10 Nov 2008 03:55:08 -0500 In-Reply-To: <20081110083938.GD22392@elte.hu> Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Ingo Molnar Cc: "H. Peter Anvin" , "Eric W. Biederman" , Andrey Borzenkov , Len Brown , linux-acpi@vger.kernel.org, Len Brown , Thomas Gleixner , Eduardo Habkost , Andrew Morton Ingo Molnar wrote: > * 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 > > 2007? Maybe 2002, a year after Windows XP was launched? Windows XP uses ACPI by default. Not sure about reboot, but I wouldn't be surprised if it did, since it's such a simple feature, not involving AML etc. > 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 > Most likely ACPI uses port CF9 if it's available. > ... 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. > What the vmx issues showed us is that keyboard reset is unreliable on some machines, so reset was actually done by triple-fault, which doesn't work well when vmx is enabled (if it's connected to INIT; note it won't reset peripherals in that case). -- error compiling committee.c: too many arguments to function