Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754073AbaDDRon (ORCPT ); Fri, 4 Apr 2014 13:44:43 -0400 Received: from mail-wg0-f45.google.com ([74.125.82.45]:34511 "EHLO mail-wg0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753270AbaDDRol (ORCPT ); Fri, 4 Apr 2014 13:44:41 -0400 Date: Fri, 4 Apr 2014 19:44:37 +0200 From: Ingo Molnar To: "H. Peter Anvin" Cc: Matthew Garrett , "Li, Aubrey" , Steven Rostedt , Linus Torvalds , LKML , Thomas Gleixner Subject: Re: [BUG] x86: reboot doesn't reboot Message-ID: <20140404174437.GC25173@gmail.com> References: <533DED74.6050202@linux.intel.com> <20140403194018.7c67aec7@gandalf.local.home> <533DF455.4040908@linux.intel.com> <533DF8D2.9060508@zytor.com> <533E0A94.5040007@linux.intel.com> <20140404151203.GA12370@srcf.ucam.org> <533ECC2C.6090505@zytor.com> <20140404153634.GA14519@srcf.ucam.org> <20140404173431.GA25173@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * H. Peter Anvin wrote: > The comment header is bogus... it describes what we do, not what > Windows does. That comment certainly pretends to describe Windows behavior and then it goes to outline the differences in Linux behavior: /* * Windows compatible x86 hardware expects the following on reboot: * * 1) If the FADT has the ACPI reboot register flag set, try it * 2) If still alive, write to the keyboard controller * 3) If still alive, write to the ACPI reboot register again * 4) If still alive, write to the keyboard controller again * 5) If still alive, call the EFI runtime service to reboot * 6) If still alive, write to the PCI IO port 0xCF9 to reboot * 7) If still alive, inform BIOS to do a proper reboot * * If the machine is still alive at this stage, it gives up. We default to * following the same pattern, except that if we're still alive after (7) we'll * try to force a triple fault and then cycle between hitting the keyboard * controller and doing that */ (The 'we default' means 'Linux defaults'.) So that comment should be fixed to describe the hardware ABI (Windows behavior), to the extent it is known - and then outline where and why Linux deviates from that. (and preferably it should match Windows behavior and only _add_ to that behavior at the end of the reboot sequence.) Before any other change is done beyond the revert of this latest broken commit. Thanks, 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/