From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755532AbcA1T6D (ORCPT ); Thu, 28 Jan 2016 14:58:03 -0500 Received: from www.linutronix.de ([62.245.132.108]:35410 "EHLO Galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750799AbcA1T6A (ORCPT ); Thu, 28 Jan 2016 14:58:00 -0500 Date: Thu, 28 Jan 2016 20:56:52 +0100 (CET) From: Thomas Gleixner To: Jeffrey Merkey cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, dzickus@redhat.com, uobergfe@redhat.com, atomlin@redhat.com, mhocko@suse.cz, fweisbec@gmail.com, tj@kernel.org, hidehiro.kawai.ez@hitachi.com, cmetcalf@ezchip.com Subject: Re: [PATCH 01/31] Add hard/soft lockup debugger entry points In-Reply-To: <1454010366-28416-1-git-send-email-jeffmerkey@gmail.com> Message-ID: References: <1454010366-28416-1-git-send-email-jeffmerkey@gmail.com> User-Agent: Alpine 2.11 (DEB 23 2013-08-11) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Linutronix-Spam-Score: -1.0 X-Linutronix-Spam-Level: - X-Linutronix-Spam-Status: No , -1.0 points, 5.0 required, ALL_TRUSTED=-1,SHORTCIRCUIT=-0.0001 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 28 Jan 2016, Jeffrey Merkey wrote: > This patch series adds an export which can be set by system debuggers to > direct the hard lockup and soft lockup detector to trigger a breakpoint > exception and enter a debugger if one is active. It is assumed that if > someone sets this variable, then an breakpoint handler of some sort will > be actively loaded or registered via the notify die handler chain. > > This addition is extremely useful for debugging hard and soft lockups > real time and quickly from a console debugger. Why do we need an extra breakpoint instruction in the code to enter a debugger? Don't have debuggers mechanisms to install breakpoints? I'm probably missing something obvious here. Thanks, tglx