From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935971AbXGZTxw (ORCPT ); Thu, 26 Jul 2007 15:53:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932950AbXGZTxo (ORCPT ); Thu, 26 Jul 2007 15:53:44 -0400 Received: from smtp2.linux-foundation.org ([207.189.120.14]:39038 "EHLO smtp2.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1763880AbXGZTxn (ORCPT ); Thu, 26 Jul 2007 15:53:43 -0400 Date: Thu, 26 Jul 2007 12:52:40 -0700 From: Andrew Morton To: Will Woods Cc: Neil Horman , linux-kernel@vger.kernel.org Subject: Re: [PATCH] core_pattern: Add ability for core_pattern to parse arguments when pattern is a pipe Message-Id: <20070726125240.645c3322.akpm@linux-foundation.org> In-Reply-To: <1185478584.15670.31.camel@metroid.rdu.redhat.com> References: <20070726173923.GA5701@hmsreliant.homelinux.net> <20070726114832.faf14bb0.akpm@linux-foundation.org> <1185478584.15670.31.camel@metroid.rdu.redhat.com> X-Mailer: Sylpheed 2.4.1 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 26 Jul 2007 15:36:24 -0400 Will Woods wrote: > On Thu, 2007-07-26 at 11:48 -0700, Andrew Morton wrote: > > On Thu, 26 Jul 2007 13:40:19 -0400 Neil Horman wrote: > > > > > Currently, core dumps can be redirected to a pipe by placing the > > > following string template in /proc/sys/kernel/core_pattern: > > > | > > > This patch extends this ability, allowing the core_pattern to contain arguments > > > to be passed as an argv array to the userspace helper application. It also add > > > a format specifier, %c, which allows the RLIM_CORE value of the crashing > > > application to be passed on the command line, since RLIMIT_CORE is reduced to > > > zero when execing the userspace helper > > > > This all seems to be getting a bit nutty. Who needs this feature > > and what will they do with it, etc? > > We're using it for doing a system-wide crash dump handler. Currently > Ubuntu's using it with their Apport tool[1] for this purpose; I'm > adapting that for Fedora. Can you please copy the relevant Ubuntu people on the patches then? It would be valuable to get their input on the proposal. > The Ubuntu approach requires a kernel patch that adds a bunch of process > information (process pid, RLIMIT_CORE, etc) to the environment of the > crash handler[2]. Most of that information can instead be parsed out of > the ELF headers - which is what I wrote code to do[3]. The problem that > remains is determining the value of RLIMIT_CORE. (This is used to > determine whether the user wants a normal corefile, thus retaining > normal core dump behavior). > > As I understand it, getrlimit() won't return the correct values while > dumping to a pipe. So we need to pass the original RLIMIT_CORE to the > userspace helper somehow. It seems sensible to pass arguments to a > userspace program by using argv[]. So there we are. yup. The changelog should clearly document this new kernel/userspace interface, please. Things like what the argv format will be, which args are optional, etc. > There's probably many other uses for this stuff but that's the specific > one we're targeting. Does that make sense? If there's an easier way to > get the original RLIMIT_CORE from inside the crash handler, I'd love to > hear it. > I'm still emerging from the "what the heck is this" state ;) You need to tell us these things...