From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7083 invoked by alias); 26 Jul 2003 23:29:53 -0000 Mailing-List: contact gdb-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sources.redhat.com Received: (qmail 7066 invoked from network); 26 Jul 2003 23:29:52 -0000 Received: from unknown (HELO mx1.redhat.com) (66.187.233.31) by sources.redhat.com with SMTP; 26 Jul 2003 23:29:52 -0000 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.11.6/8.11.6) with ESMTP id h6QNTqH06266 for ; Sat, 26 Jul 2003 19:29:52 -0400 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [172.16.52.156]) by int-mx1.corp.redhat.com (8.11.6/8.11.6) with ESMTP id h6QNTqI11560 for ; Sat, 26 Jul 2003 19:29:52 -0400 Received: from localhost.redhat.com (romulus-int.sfbay.redhat.com [172.16.27.46]) by pobox.corp.redhat.com (8.11.6/8.11.6) with ESMTP id h6QNTpv29067 for ; Sat, 26 Jul 2003 19:29:51 -0400 Received: by localhost.redhat.com (Postfix, from userid 469) id F17042CB2D; Sat, 26 Jul 2003 19:37:12 -0400 (EDT) From: Elena Zannoni MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16163.4264.817155.564263@localhost.redhat.com> Date: Sat, 26 Jul 2003 23:29:00 -0000 To: Daniel Jacobowitz Cc: gdb@sources.redhat.com Subject: Re: RFC: A mode in which gdb avoids libthread_db In-Reply-To: <20030726155820.GA1063@nevyn.them.org> References: <20030726155820.GA1063@nevyn.them.org> X-SW-Source: 2003-07/txt/msg00314.txt.bz2 Daniel Jacobowitz writes: > Recent Linux kernels (2.5.30 and later; theoretically the latest Red Hat > 2.4.20 kernels also include it, but I observed some badness in testing...) > support some ptrace extensions I designed which make it possible to debug > multi-threaded applications without using libthread_db at all. The only > things we'll lose are: > - Potential high-level information, like mutex status - right now we > don't have this at all on GNU/Linux. > - TLS access - this could be easily fixed by handling each platform's > TLS ABI directly from GDB, and there's a comment to that effect in > GDB's source already. > - TIDs - we'd only have the application's LWP IDs, not the thread IDs > that LinuxThreads/NPTL use. > > Things we'll gain: > - A lot of libthread_db-related bugs would go away. For instance, > the kfail in print-threads.exp, which hits a breakpoint after > LinuxThreads decides the thread has already exited. > - ABI simplicity - this would solve the x86-64/i386 issue, and similar > problems on MIPS. > - Support for debugging clone-based 1-1 threading which doesn't use > libpthread.so. > > Once the pending fork-debugging patch is accepted, most of the machinery > we'd need to do it will be in place, too. Thoughts? Worthwhile? I know first hand of the pains of mismatched glibcs, binutils, kernels, gdbs. I wouldn't mind having this coexist with the use of glibc, is that possible? What ptrace changes did you do? (Elena needs to start reading linux-kernel) elena > > -- > Daniel Jacobowitz > MontaVista Software Debian GNU/Linux Developer