From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13320 invoked by alias); 24 Jun 2008 19:34:46 -0000 Received: (qmail 13310 invoked by uid 22791); 24 Jun 2008 19:34:45 -0000 X-Spam-Check-By: sourceware.org Received: from bluesmobile.specifix.com (HELO bluesmobile.specifix.com) (216.129.118.140) by sourceware.org (qpsmtpd/0.31) with ESMTP; Tue, 24 Jun 2008 19:34:21 +0000 Received: from [127.0.0.1] (bluesmobile.specifix.com [216.129.118.140]) by bluesmobile.specifix.com (Postfix) with ESMTP id 23E993BF23; Tue, 24 Jun 2008 12:34:20 -0700 (PDT) Subject: Re: [RFA] set/show enable-software-singlestep From: Michael Snyder To: luisgpm@linux.vnet.ibm.com Cc: gdb-patches@sourceware.org In-Reply-To: <1214335779.10496.21.camel@gargoyle> References: <1214331534.3601.1211.camel@localhost.localdomain> <1214335779.10496.21.camel@gargoyle> Content-Type: text/plain Date: Tue, 24 Jun 2008 20:22:00 -0000 Message-Id: <1214336059.3601.1222.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.3 (2.10.3-7.fc7) Content-Transfer-Encoding: 7bit X-IsSubscribed: yes Mailing-List: contact gdb-patches-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sourceware.org X-SW-Source: 2008-06/txt/msg00419.txt.bz2 On Tue, 2008-06-24 at 16:29 -0300, Luis Machado wrote: > On Tue, 2008-06-24 at 11:18 -0700, Michael Snyder wrote: > > There may be cases where gdb would be inclined to use > > software singlestep, but you might not want it to. Examples: > > > > * "target remote" to a target such as a simulator that > > would be able to support normal singlestep. > > > > * reverse debugging, where you can't predict the > > "come-from" address of a jump instruction. > > > > What do you guys think? Useful? > > It's a useful feature and looks OK. I'm just wondering how dangerous it > would be to turn software single stepping off on PPC64 and stumble upon > an atomic sequence and end up locked there (we use software single > stepping explicitly to jump those sequences). Well, it would be dangerous (ie. fatal) any time when software singlestep is actually required. It's only meant for when you know it isn't required, even though normally it would be. In my revised patch, I've made it a "maintainer" command. Later if we decide that users can be trusted with it, we can promote it. ;-)