Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754148Ab1CUU15 (ORCPT ); Mon, 21 Mar 2011 16:27:57 -0400 Received: from mail-iy0-f174.google.com ([209.85.210.174]:47386 "EHLO mail-iy0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752362Ab1CUU1z (ORCPT ); Mon, 21 Mar 2011 16:27:55 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:cc:content-type; b=Exj7g92wgTloehre7GHKlLWB274Q1pz2R86f2GzIwrPrlAdcBuOGuBqGTwYU8n9xX3 dfNTSizLqh77yJCRgXpmRUayl0JBu9d9IhJB7TDKr66M++on5u5vdGyHbJd4P35LLkFH YU4PKOKq12uIluMGKJcwrooOAI27QSvA5l3CA= MIME-Version: 1.0 In-Reply-To: <5C4C569E8A4B9B42A84A977CF070A35B2C14F5A465@USINDEVS01.corp.hds.com> References: <4d8797d74168a6441@agluck-desktop.sc.intel.com> <5C4C569E8A4B9B42A84A977CF070A35B2C14F5A465@USINDEVS01.corp.hds.com> Date: Mon, 21 Mar 2011 13:27:54 -0700 X-Google-Sender-Auth: DF6g3WTv40dEaFQ7aTVyViRkxKE Message-ID: Subject: Re: [RFC] pstore: Don't use persistent store for normal shutdown From: Tony Luck To: Seiji Aguchi Cc: "linux-kernel@vger.kernel.org" , David Woodhouse , Marco Stornelli , Artem Bityutskiy , KOSAKI Motohiro , Andrew Morton , Linus Torvalds Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1478 Lines: 35 On Mon, Mar 21, 2011 at 12:49 PM, Seiji Aguchi wrote: > I think we should save the tail of kernel log into persistent store > for both every shutdown and kexec path because these data are useful > in enterprise area. > > I already described the useful case in lkml (see below). > > normal shutdown: > https://lkml.org/lkml/2010/11/17/249 I hadn't thought about the forensic opportunities to show that a reboot/halt was the cause of a server shutdown - but these do look useful. Should I still try to save as much data in these cases? Saving 1 Kbyte would be enough to have the last dozen+ lines, including the critical <0>[ 536.970556] Restarting system. that you'd like to see. > kexec: > https://lkml.org/lkml/2011/2/23/325 In the case of kexec used as a "fast reboot" to another kernel, it might also be valid to save some small amount of kernel log - but in the case of kexec to take a kernel dump after a serious problem, it might be good to have as much kernel log as possible to make sure that we have no gaps in saved data. If there isn't an easy way to tell these two kexec cases apart, we should just save more data in both cases. I'll make a new patch incorporating these changes. -Tony -- 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/