From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933892Ab3D3WaJ (ORCPT ); Tue, 30 Apr 2013 18:30:09 -0400 Received: from hydra.sisk.pl ([212.160.235.94]:51756 "EHLO hydra.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933783Ab3D3WaD (ORCPT ); Tue, 30 Apr 2013 18:30:03 -0400 From: "Rafael J. Wysocki" To: Konrad Rzeszutek Wilk Cc: mingo@kernel.org, hpa@zytor.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, hpa@linux.intel.com, linux-tip-commits@vger.kernel.org Subject: Re: [tip:x86/paravirt] x86-64, gdt: Store/ load GDT for ACPI S3 or hibernate/resume path is not needed. Date: Wed, 01 May 2013 00:38:17 +0200 Message-ID: <2307239.2tnNighu20@vostro.rjw.lan> User-Agent: KMail/4.9.5 (Linux/3.9.0+; KDE/4.9.5; x86_64; ; ) In-Reply-To: <20130430212542.GA19753@phenom.dumpdata.com> References: <1365194544-14648-2-git-send-email-konrad.wilk@oracle.com> <4054620.GA2vTd0F6g@vostro.rjw.lan> <20130430212542.GA19753@phenom.dumpdata.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="utf-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday, April 30, 2013 05:25:42 PM Konrad Rzeszutek Wilk wrote: > > > After the 'restore_registers' it returns and we end up called > > > restore_processor_state() - where we reload the GDT. The reload of > > > the GDT is not needed as bootup kernel has already loaded the GDT which > > > is at the same physical location as the the restored kernel. > > > > I'm not sure if this particular statement is actually correct. It is correct > > on 32-bit, but here it is not necessary for the bootup kernel to be the same > > as the image one. Different kernel version may be used for that even (at > > least theoretically). So the question is, and I'm quite unsure about the > > answer, if the GDT of from the bootup kernel is really *guaranteed* to be > > at the same location (given that those kernels may be really different). > > A bit of testing with different bootup kernel provided me with this error: > PM: Image mismatch: version This implies that you tested on an architechture without CONFIG_ARCH_HIBERNATION_HEADER. > which after a bit of digging pointed me to 'check_image_kernel'. The criteria > there imply that the different kernel versions or releases cannot be used with > hibernation. Only if CONFIG_ARCH_HIBERNATION_HEADER is unset, which is not the case for CONFIG_X86_64. Thanks, Rafael -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center.