From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [patch] hibernation: utilize ACPI hardware signature Date: Wed, 2 Jan 2008 15:05:39 +0100 Message-ID: <200801021505.39789.rjw@sisk.pl> References: <1199257162.14632.4.camel@sli10-desk.sh.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Return-path: Received: from ogre.sisk.pl ([217.79.144.158]:41552 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752165AbYABODi (ORCPT ); Wed, 2 Jan 2008 09:03:38 -0500 In-Reply-To: <1199257162.14632.4.camel@sli10-desk.sh.intel.com> Content-Disposition: inline Sender: linux-acpi-owner@vger.kernel.org List-Id: linux-acpi@vger.kernel.org To: Shaohua Li Cc: pm list , linux acpi , Len Brown , Pavel Machek On Wednesday, 2 of January 2008, Shaohua Li wrote: > ACPI defines a hardware signature. BIOS calculates the signature > according to hardware configure, if hardware changes, the signature will > change, in this case, S4 resume should fail. The idea is fine, but I'd prefer to do that in a more straightforward way. Namely, we can just: * write the signature into a variable in, for example, acpi_hibernation_prepare() (then, the "old" signature value will be automatically saved in the image) * compare it with a the "new" value read from the BIOS in acpi_hibernation_leave() and panic if there's a mismatch * add a configuration option to disable this behavior (just in case) This way we can avoid modifying the entire generic interface to add the feature specific to ACPI. Still, if you want the boot kernel to check the signature, which will be more elegant (but please note that on x86-64 the boot kernel need not support ACPI at all), you can use the (recently introduced) architecture part of the image header for this purpose, without modifying the generic interface. Greetings, Rafael