From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 3491 invoked by alias); 25 Jan 2011 09:35:48 -0000 Received: (qmail 3325 invoked by uid 22791); 25 Jan 2011 09:35:47 -0000 X-SWARE-Spam-Status: No, hits=-6.9 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_HI,SPF_HELO_PASS,T_RP_MATCHES_RCVD X-Spam-Check-By: sourceware.org Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Tue, 25 Jan 2011 09:35:40 +0000 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.13.8/8.13.8) with ESMTP id p0P9ZVOR006445 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 25 Jan 2011 04:35:31 -0500 Received: from jolsa.brq.redhat.com (dhcp-1-174.brq.redhat.com [10.34.1.174]) by int-mx01.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with SMTP id p0P9ZUXH021672; Tue, 25 Jan 2011 04:35:30 -0500 Date: Tue, 25 Jan 2011 09:35:00 -0000 From: Jiri Olsa To: Yao Qi Cc: gdb@sourceware.org Subject: Re: [RFC] gelf - user space probe debugger Message-ID: <20110125093529.GA3579@jolsa.brq.redhat.com> References: <20110124161020.GC3694@jolsa.brq.redhat.com> <4D3DFEBC.8030508@codesourcery.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4D3DFEBC.8030508@codesourcery.com> User-Agent: Mutt/1.5.21 (2010-09-15) Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org X-SW-Source: 2011-01/txt/msg00108.txt.bz2 On Tue, Jan 25, 2011 at 06:35:40AM +0800, Yao Qi wrote: > On 01/25/2011 12:10 AM, Jiri Olsa wrote: > > hi, > > > > I started a debugger project. It's based on the user space backport > > of optimized kprobes (djprobes) and RSP stub implementation. > > > > First of all, it is a nice piece of work! > thanks > > The debugger is implemented as a preloaded shared library, > > which handles all the debugger work, hence no kernel ptrace > > is needed. > > Here are some questions, and I am sorry if my questions go out of scope > here. > 1. Do you plan to handle signal without ptrace support? In > ptrace-debugger, we can know every signal delivered to debuggee process. > How can we do that in your probe-debugger? haven't thought about that, but I guess the only option would be to take over the signal handlers and somehow call the user handlers.. also intercept the signal handling routines (signal/sigaction..) ..seems tricky ;) > > 2. Do you plan to support hardware single-step on x86? > I haven't thought that far ahead.. looks like it might be possible via setting the TRAP flag and handling SIGTRAP > > > > I'd like to ask for opinions if there'd be users for such thing, > > and if it's worth to continue on this.. > > AFAIK, it is not easy to replace ptrace-based debugger by probe-based > debugger completely. However, probe-based technology can be a > complementary part to existing ptrace-based debugger, especially to > efficient implementation of breakpoint/watchpoint/tracepoint in some > cases. Shortly, it is good to put both ptrace-based and probe-based > into single debugger, and maximize their advantages, and minimize their > disadvantages. yep, makes sense, I'll think about it.. thanks a lot for feedback jirka