From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 26326 invoked by alias); 18 Feb 2003 03:14:36 -0000 Mailing-List: contact gdb-patches-help@sources.redhat.com; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-patches-owner@sources.redhat.com Received: (qmail 26319 invoked from network); 18 Feb 2003 03:14:36 -0000 Received: from unknown (HELO crack.them.org) (65.125.64.184) by 172.16.49.205 with SMTP; 18 Feb 2003 03:14:36 -0000 Received: from nevyn.them.org ([66.93.61.169] ident=mail) by crack.them.org with asmtp (Exim 3.12 #1 (Debian)) id 18l06T-0002lz-00; Mon, 17 Feb 2003 23:15:37 -0600 Received: from drow by nevyn.them.org with local (Exim 3.36 #1 (Debian)) id 18kyDH-0008Hl-00; Mon, 17 Feb 2003 22:14:31 -0500 Date: Tue, 18 Feb 2003 03:14:00 -0000 From: Daniel Jacobowitz To: Andrew Cagney Cc: Elena Zannoni , gdb-patches@sources.redhat.com Subject: Re: [RFC] PTRACE_ATTACH problem on new Linux kernels Message-ID: <20030218031431.GA31807@nevyn.them.org> Mail-Followup-To: Andrew Cagney , Elena Zannoni , gdb-patches@sources.redhat.com References: <15953.34032.985446.344226@localhost.redhat.com> <20030218022401.14C7E3CF3@localhost.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20030218022401.14C7E3CF3@localhost.redhat.com> User-Agent: Mutt/1.5.1i X-SW-Source: 2003-02/txt/msg00364.txt.bz2 On Mon, Feb 17, 2003 at 09:24:01PM -0500, Andrew Cagney wrote: > Solution 0 is to discard the STOP in infrun.c as part of the stop > analyzis. I like this; but I can't think how to do it without some global state bit saying just-attached-expecting-SIGSTOP. > > > A first solution could be that upon continuing, gdb never sends a > > SIGSTOP through the ptrace call. I.e. the stop_signal in > > ptrace(PTRACE_CONT, pid, stop_signal) could be changed to > > TARGET_SIGNAL_0 if it is TARGET_SIGNAL_STOP (such a call is in > > proceed(), and we already do some signal munging there). > > > > Another solution is to throw away the TARGET_SIGNAL_STOP that is saved > > in stop_signal when we do an attach. This would be in > > attach_command(), in infcmd.c. This way it would not come into play at > > all at the next continue. > > This will make the desperatly needed objective of trying to eliminate > the global stop_signal variable just that bit more difficult. > > If the already nasty hacks in HP/PA and solib code is ignored, the > only places stop_signal is modified is in infrun.c. > > > Yet another solution is that we 'hide' the TARGET_SIGNAL_STOP in > > child_resume(), in i386-linux-nat.c but this would not be applicable > > to the other linux arches. > > Or discard the signal in resume()? > > Regardless, remembering that GDB is just one client of the kernel, the > kernel group should probably also restore the behavour that is > conistent with solaris and (most likely) every other ptrace > implementation. I'm not sure what Solaris does - don't we use procfs instead of ptrace there anyway? Do we still get a SIGSTOP at attach? But Roland made a very convincing case for this new behavior; for programs like strace which just pass all signals through, this prevents SIGSTOPs being silently cancelled, which is a definite plus. -- Daniel Jacobowitz MontaVista Software Debian GNU/Linux Developer