Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754072AbYKDKs6 (ORCPT ); Tue, 4 Nov 2008 05:48:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751314AbYKDKsu (ORCPT ); Tue, 4 Nov 2008 05:48:50 -0500 Received: from mx2.redhat.com ([66.187.237.31]:37610 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751082AbYKDKst (ORCPT ); Tue, 4 Nov 2008 05:48:49 -0500 Message-ID: <4910283B.4070501@redhat.com> Date: Tue, 04 Nov 2008 12:47:23 +0200 From: Avi Kivity User-Agent: Thunderbird 2.0.0.16 (X11/20080723) MIME-Version: 1.0 To: "Eric W. Biederman" CC: Eduardo Habkost , Ingo Molnar , Andrey Borzenkov , mingo@redhat.com, Andrew Morton , "Rafael J. Wysocki" , Linux Kernel Mailing List Subject: Re: [PATCH] Use BIOS reboot on Toshiba Portege 4000 References: <200810312118.45368.arvidjaar@mail.ru> <20081103090843.GI11730@elte.hu> <490ECC4D.9090704@redhat.com> <20081103133306.GZ23893@blackpad> <490F0DA3.4090108@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1696 Lines: 47 Eric W. Biederman wrote: > I think we are confusing two issues here. > > - Ordinary machine_restart which happens to call emergency_restart. > And is proceeded by machine_shutdown. > > - And emergency_restart itself. > > To some extent I would be a lot happier if Alt-sysrq-r did what > was necessary to get into a context where it can call machine_restart > or even better kernel_restart(). > emergency_restart() is a nice idea but is broken by design. > > Isn't emergency_restart() equivalent to kexec()? Both start from indeterminite conditions. > That said. If we can turn off vmx on that one processor. > That should be enough for the cpu to triple fault and let > the BIOS do what it needs to do on that cpu i.e. outb(magic, 0x92) > and toggle a motherboard level reset? > > If triple fault is wired to INIT (as it is at least on some systems; for example one of mine) then the cpu will reset, but why will the bios proceed to issue a motherboard reset? Won't it happily POST it's way to boot (leaving the other cpus dead)? > If I read the earlier comments correctly the deep issue is > that going through ACPI to reset systems is less reliable than > doing it the classic way. > It depends on the system; both are unreliable. But if we use the same trick as with kdump (NMI SIPI + vmxoff) the choice will be orthogonal to whether vmx is in use or not. -- error compiling committee.c: too many arguments to function -- 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/