From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267358AbUGNK4N (ORCPT ); Wed, 14 Jul 2004 06:56:13 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267362AbUGNK4N (ORCPT ); Wed, 14 Jul 2004 06:56:13 -0400 Received: from mail.ocs.com.au ([202.147.117.210]:36291 "EHLO mail.ocs.com.au") by vger.kernel.org with ESMTP id S267358AbUGNK4L (ORCPT ); Wed, 14 Jul 2004 06:56:11 -0400 X-Mailer: exmh version 2.6.3_20040314 03/14/2004 with nmh-1.0.4 From: Keith Owens To: Jeff Garzik Cc: linux-kernel@vger.kernel.org Subject: Re: [RFC] Standard filesystem types for crash dumping In-reply-to: Your message of "Wed, 14 Jul 2004 03:49:35 -0400." <40F4E58F.7040204@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Wed, 14 Jul 2004 20:55:56 +1000 Message-ID: <3307.1089802556@ocs3.ocs.com.au> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 14 Jul 2004 03:49:35 -0400, Jeff Garzik wrote: >Keith Owens wrote: >> Follow ups to lkml please, to keep any discussion on the same list. >> >> Several kernel additions exist for saving crash dump information, among >> them are lkcd, crash, kmsgdump. They all have the same problems :- >> >> * Where to store the crash data. >> * How to write data when the kernel is unreliable, it may not be >> servicing interrupts. >> * User space needs to read and clear the dump data. >> * Performance! >> * Coexistence of multiple dump drivers. > > >Have you tried diskdump? > >It already exists, and seems to address these things. diskdump adds polling mode disk I/O, but the polling code is tied to the diskdump code path, so it cannot easily be used by other dump code. It was while I was trying to generalize diskdump that I realized we keep reinventing this particular wheel, both in kernel and user space. diskdump only handles one device, that device cannot be used for other dump tools and it needs special user space tools to extract the data. As I said further down the original RFC, I am using the polling code from diskdump but converting it to a clean API that can be used by any dump code, as well as removing the need for special user space tools to dig into partitions to see what has been dumped.