Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751805AbXE0Ila (ORCPT ); Sun, 27 May 2007 04:41:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751150AbXE0IlV (ORCPT ); Sun, 27 May 2007 04:41:21 -0400 Received: from s2.ukfsn.org ([217.158.120.143]:44133 "EHLO mail.ukfsn.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751114AbXE0IlU (ORCPT ); Sun, 27 May 2007 04:41:20 -0400 Message-ID: <4659442E.2060307@dgreaves.com> Date: Sun, 27 May 2007 09:41:18 +0100 From: David Greaves User-Agent: Icedove 1.5.0.10 (X11/20070329) MIME-Version: 1.0 To: Bill Davidsen Cc: Linux Kernel M/L Subject: Re: [2.6.21.1] resume doesn't run suspended kernel? References: <4658B7DD.3060309@tmr.com> In-Reply-To: <4658B7DD.3060309@tmr.com> X-Enigmail-Version: 0.94.2.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1500 Lines: 37 Bill Davidsen wrote: > Anyway, I pulled the plug on the UPS, and the system shut down. But when > it powered up, it booted the default kernel rather than the test kernel, > decided that it couldn't resume, and then did a cold boot. Booting the machine isn't the kernel's job, it's the bootloader's job. > I can bypass this by making the debug kernel the default, but WHY? Is > the kernel not saved such that any kernel can be rolled back into memory > and run? Actually, the answer is HELL NO, so I really ask if this is the > intended mode of operation, that only the default boot kernel will restore. Yes. It is very dangerous to attempt a resume with a different kernel than the one that has gone to sleep. Different kernels may be compiled with different options that affect where or how in-memory structures are saved. So you suspend with a kernel which holds your filesystem data/cache/inodes at 0x1234000 and restore with a kernel that expects to see your filesystem data at 0x1235000. Ouch. Personally I think the kernel suspend should write a signature - similar to a hash of the bzImage - into the suspend image so it won't even attempt a resume if there's a mismatch. (Yes, I made this mistake once whilst playing with suspend). David - 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/