From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11051 invoked by alias); 19 Apr 2011 20:01:12 -0000 Received: (qmail 11043 invoked by uid 22791); 19 Apr 2011 20:01:11 -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, 19 Apr 2011 20:00:53 +0000 Received: from int-mx02.intmail.prod.int.phx2.redhat.com (int-mx02.intmail.prod.int.phx2.redhat.com [10.5.11.12]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id p3JK0j8K005372 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Tue, 19 Apr 2011 16:00:45 -0400 Received: from ns3.rdu.redhat.com (ns3.rdu.redhat.com [10.11.255.199]) by int-mx02.intmail.prod.int.phx2.redhat.com (8.13.8/8.13.8) with ESMTP id p3JK0iwV006612; Tue, 19 Apr 2011 16:00:45 -0400 Received: from opsy.redhat.com (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by ns3.rdu.redhat.com (8.13.8/8.13.8) with ESMTP id p3JK0itX027962; Tue, 19 Apr 2011 16:00:44 -0400 Received: by opsy.redhat.com (Postfix, from userid 500) id C7B6837800C; Tue, 19 Apr 2011 14:00:43 -0600 (MDT) From: Tom Tromey To: Pedro Alves Cc: gdb-patches@sourceware.org, Sergio Durigan Junior Subject: Re: [PATCH 3/6] Modify internalvar mechanism References: <201104121224.31901.pedro@codesourcery.com> <201104191852.58106.pedro@codesourcery.com> Date: Tue, 19 Apr 2011 20:01:00 -0000 In-Reply-To: (Tom Tromey's message of "Tue, 19 Apr 2011 12:39:37 -0600") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii 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: 2011-04/txt/msg00340.txt.bz2 Pedro> I noticed that patch 4 does some changes to Pedro> start_tracing to tweak the probes' semaphores, if any. Pedro> What are these semaphores? How do other stap tools Pedro> handle them? I ask because that bends a bit the definition Pedro> of "trace" being a regular tracepoint at a given Pedro> location, so I'd like to understand it. While developing this, Sergio and I talked extensively to Roland and the other SystemTap guys about the sdt.h implementation. Today I finally got around to writing up our notes: http://sourceware.org/systemtap/wiki/UserSpaceProbeImplementation There is already some documentation about adding probes: http://sourceware.org/systemtap/wiki/AddingUserSpaceProbingToApps .. though it seems to focus a bit too much (IMO) on the dtrace compatibility aspect. You can see a simpler approach in the test suite part of patch #4 -- you don't actually need anything more than the #include. Tom