From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161029AbWGNKnQ (ORCPT ); Fri, 14 Jul 2006 06:43:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161047AbWGNKnQ (ORCPT ); Fri, 14 Jul 2006 06:43:16 -0400 Received: from omx2-ext.sgi.com ([192.48.171.19]:49821 "EHLO omx2.sgi.com") by vger.kernel.org with ESMTP id S1161029AbWGNKnQ (ORCPT ); Fri, 14 Jul 2006 06:43:16 -0400 Date: Fri, 14 Jul 2006 03:42:44 -0700 From: Paul Jackson To: Ingo Molnar Cc: torvalds@osdl.org, ak@suse.de, acahalan@gmail.com, alan@lxorguk.ukuu.org.uk, arjan@infradead.org, akpm@osdl.org, linux-kernel@vger.kernel.org, roland@redhat.com Subject: Re: utrace vs. ptrace Message-Id: <20060714034244.87b95930.pj@sgi.com> In-Reply-To: <20060713194735.GA27807@elte.hu> References: <787b0d920607122243g24f5a003p1f004c9a1779f75c@mail.gmail.com> <200607131437.28727.ak@suse.de> <20060713124316.GA18852@elte.hu> <200607131521.52505.ak@suse.de> <20060713194735.GA27807@elte.hu> Organization: SGI X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.3; i686-pc-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 Ingo wrote: > it wouldnt be fundamentally easier - but lots of policy stuff could be > done there which we would otherwise reject to add to the kernel. Like > more complex rules for "do we want to dump core for this particular > app". Reading this brought to mind the 'user exit' hooks that are common in IBM's mainframe O.S.'s. Their system code does what system code does (and likely a whole lot more than Linux would consider doing.) But they also provide many places for user level code to get called off a variety of hooks, to allow for special cases. I had fantasies of our core dumping code using call_usermodehelper() to call a user command by a well known path, passing it the pid of the corpse. While waiting for the user command to exit, the kernel would accept non-default core dump settings via special /sys or /proc files for that pid. The user mode helper command could set these options before returning (by exiting) to the kernel for the core dump to be processed. By default, the user command would do nothing but exit and the core dump would proceed as it does now. -- I won't rest till it's the best ... Programmer, Linux Scalability Paul Jackson 1.925.600.0401