From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 23678 invoked by alias); 23 Nov 2008 21:15:47 -0000 Received: (qmail 23565 invoked by uid 22791); 23 Nov 2008 21:15:46 -0000 X-Spam-Check-By: sourceware.org Received: from NaN.false.org (HELO nan.false.org) (208.75.86.248) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sun, 23 Nov 2008 21:15:06 +0000 Received: from nan.false.org (localhost [127.0.0.1]) by nan.false.org (Postfix) with ESMTP id 526581059A; Sun, 23 Nov 2008 21:14:56 +0000 (GMT) Received: from caradoc.them.org (209.195.188.212.nauticom.net [209.195.188.212]) by nan.false.org (Postfix) with ESMTP id 0E78A104A1; Sun, 23 Nov 2008 21:14:56 +0000 (GMT) Received: from drow by caradoc.them.org with local (Exim 4.69) (envelope-from ) id 1L4MIA-0004c8-V7; Sun, 23 Nov 2008 16:14:55 -0500 Date: Mon, 24 Nov 2008 13:53:00 -0000 From: Daniel Jacobowitz To: gdb-patches@sourceware.org Cc: Pedro Alves , dgraham@nortel.com Subject: RFC: Do not try g-packet-guess algorithm on exited targets Message-ID: <20081123211454.GA17391@caradoc.them.org> Mail-Followup-To: gdb-patches@sourceware.org, Pedro Alves , dgraham@nortel.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.17 (2008-05-11) 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: 2008-11/txt/msg00626.txt.bz2 We got a bug report indicating that gdbserver --multi didn't work on MIPS. We'd connect to the target, try to read the XML description - gdbserver reports an error because there's no process yet - and then try to guess the description from the g packet length instead. Of course we can't do that; there's no process yet. This patch fixes the problem. We try qXfer on connection, then try 'g' only if (A) there was no XML description, and (B) there is a running process, and (C) we are not in non-stop mode; assume that non-stop targets can provide a description explicitly. Pedro, could you take a look at this before I commit it? Tested on x86 with various local changes to make sure the new code was covered; it fixes ext-attach.exp there. I'll try it on MIPS now. -- Daniel Jacobowitz CodeSourcery 2008-11-23 Daniel Jacobowitz PR gdb/2474 * remote.c (remote_read_description_p): New function. (struct remote_state): New field tdesc_no_register_access. (remote_start_remote): Try to fetch the target description without any register access, then try with register access if the target is running. (remote_read_description): Honor tdesc_no_register_access. Index: remote.c =================================================================== RCS file: /cvs/src/src/gdb/remote.c,v retrieving revision 1.329 diff -u -p -r1.329 remote.c --- remote.c 19 Nov 2008 14:45:09 -0000 1.329 +++ remote.c 23 Nov 2008 21:09:02 -0000 @@ -234,6 +234,8 @@ static void remote_async_get_pending_eve static void remote_terminal_ours (void); +static int remote_read_description_p (struct target_ops *target); + /* The non-stop remote protocol provisions for one pending stop reply. This is where we keep it until it is acknowledged. */ @@ -303,6 +305,10 @@ struct remote_state /* True if the stub reports support for vCont;t. */ int support_vCont_t; + + /* True if we are just connecting, and should not try fetching registers + yet. */ + int tdesc_no_register_access; }; /* Returns true if the multi-process extensions are in effect. */ @@ -2549,15 +2555,19 @@ remote_start_remote (struct ui_out *uiou getpkt (&rs->buf, &rs->buf_size, 0); } + /* Next, if the target can specify a description, read it. We do + this before anything involving memory or registers. At this + point, do not try to read registers from the target - it might + not be running, or it might be running and not stopped. */ + rs->tdesc_no_register_access = 1; + target_find_description (); + rs->tdesc_no_register_access = 0; + /* On OSs where the list of libraries is global to all processes, we fetch them early. */ if (gdbarch_has_global_solist (target_gdbarch)) solib_add (NULL, args->from_tty, args->target, auto_solib_add); - /* Next, if the target can specify a description, read it. We do - this before anything involving memory or registers. */ - target_find_description (); - if (non_stop) { if (!rs->non_stop_aware) @@ -2643,6 +2653,17 @@ remote_start_remote (struct ui_out *uiou get_offsets (); /* Get text, data & bss offsets. */ + /* If we could not find a description using qXfer, and we know + how to do it some other way, try again. This is not + supported for non-stop; it could be, but it is tricky if + there are no stopped threads when we connect. */ + if (remote_read_description_p (args->target) + && gdbarch_target_desc (target_gdbarch) == NULL) + { + target_clear_description (); + target_find_description (); + } + /* Use the previously fetched status. */ gdb_assert (wait_status != NULL); strcpy (rs->buf, wait_status); @@ -7852,12 +7873,32 @@ register_remote_g_packet_guess (struct g VEC_safe_push (remote_g_packet_guess_s, data->guesses, &new_guess); } +/* Return 1 if remote_read_description would do anything on this target + and architecture, 0 otherwise. */ + +static int +remote_read_description_p (struct target_ops *target) +{ + struct remote_g_packet_data *data + = gdbarch_data (target_gdbarch, remote_g_packet_data_handle); + + if (!VEC_empty (remote_g_packet_guess_s, data->guesses)) + return 1; + + return 0; +} + static const struct target_desc * remote_read_description (struct target_ops *target) { + struct remote_state *rs = get_remote_state (); struct remote_g_packet_data *data = gdbarch_data (target_gdbarch, remote_g_packet_data_handle); + /* Do not try this during initial connection. */ + if (rs->tdesc_no_register_access) + return NULL; + if (!VEC_empty (remote_g_packet_guess_s, data->guesses)) { struct remote_g_packet_guess *guess;