From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11990 invoked by alias); 27 Aug 2015 22:19:48 -0000 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 Received: (qmail 11920 invoked by uid 89); 27 Aug 2015 22:19:47 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.4 required=5.0 tests=AWL,BAYES_00,RCVD_IN_DNSWL_LOW,SPF_PASS autolearn=ham version=3.3.2 X-HELO: relay1.mentorg.com Received: from relay1.mentorg.com (HELO relay1.mentorg.com) (192.94.38.131) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 27 Aug 2015 22:19:46 +0000 Received: from svr-orw-fem-02x.mgc.mentorg.com ([147.34.96.206] helo=SVR-ORW-FEM-02.mgc.mentorg.com) by relay1.mentorg.com with esmtp id 1ZV5WI-00071b-P6 from Luis_Gustavo@mentor.com ; Thu, 27 Aug 2015 15:19:42 -0700 Received: from [172.30.12.37] (147.34.91.1) by svr-orw-fem-02.mgc.mentorg.com (147.34.96.168) with Microsoft SMTP Server id 14.3.224.2; Thu, 27 Aug 2015 15:19:42 -0700 Message-ID: <55DF8CFB.2060204@codesourcery.com> Date: Thu, 27 Aug 2015 22:19:00 -0000 From: Luis Machado Reply-To: Luis Machado User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.8.0 MIME-Version: 1.0 To: "'gdb-patches@sourceware.org'" CC: Pedro Alves Subject: qemu-system debugging broken ([PATCH 03/18] remote.c/all-stop: Implement TARGET_WAITKIND_NO_RESUMED and TARGET_WNOHANG) Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit X-IsSubscribed: yes X-SW-Source: 2015-08/txt/msg00807.txt.bz2 Just a heads-up. It looks like this particular commit... commit 567420d10895611e03d5ee65e6b24c16a69a6e99 Author: Pedro Alves Date: Fri Aug 7 17:23:56 2015 +0100 remote.c/all-stop: Implement TARGET_WAITKIND_NO_RESUMED and TARGET_WNOHANG Even though "target remote" supports target-async, the all-stop target_wait implementation ignores TARGET_WNOHANG. If the core happens to poll for events and we've already read the stop reply out of the serial/socket, remote_wait_as hangs forever instead of returning an indication that there are no events to process. This can't happen currently, but later changes will trigger this. gdb/ChangeLog: 2015-08-07 Pedro Alves * remote.c (remote_wait_as): If not waiting for a stop reply, return TARGET_WAITKIND_NO_RESUMED. If TARGET_WNOHANG is requested, don't block waiting forever. ... broke simulator-based debugging. The following is what i get when trying to run the gdb.base/break binary on qemu-system for arm eabi: _ftext () at arm-vector.S:25 25 ldr pc, [pc, #24] @ reset (gdb) load Loading section .text, size 0xc01c lma 0x0 Loading section .eh_frame, size 0x48 lma 0xc01c Loading section .ARM.exidx, size 0x8 lma 0xc064 Loading section .rodata, size 0x398 lma 0xc070 Loading section .data, size 0x8e0 lma 0xc408 Start address 0x40, load size 52452 Transfer rate: 17074 KB/sec, 1748 bytes/write. (gdb) c Continuing. infrun: clear_proceed_status_thread (Thread 1) infrun: proceed (addr=0xffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [Thread 1] at 0x40 infrun: infrun_async(1) infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = no-resumed infrun: TARGET_WAITKIND_NO_RESUMED infrun: stop_waiting infrun: clear_step_over_info No unwaited-for children left. infrun: infrun_async(0) (gdb) c Continuing. Cannot execute this command while the selected thread is running. (gdb) Continuing. Cannot execute this command while the selected thread is running. Upon further inspection, it looks like the setting of status->kind to TARGET_WAITKIND_NO_RESUMED in remote_wait_as causes GDB to stop waiting for events and marks the active thread as running, returning the GDB prompt and printing the old familiar message. Without setting TARGET_WAITKIND_NO_RESUMED, things worked fine and the binary runs to completion, like so: (gdb) load Loading section .text, size 0xc01c lma 0x0 Loading section .eh_frame, size 0x48 lma 0xc01c Loading section .ARM.exidx, size 0x8 lma 0xc064 Loading section .rodata, size 0x398 lma 0xc070 Loading section .data, size 0x8e0 lma 0xc408 Start address 0x40, load size 52452 Transfer rate: 17074 KB/sec, 1748 bytes/write. (gdb) c Continuing. infrun: clear_proceed_status_thread (Thread 1) infrun: proceed (addr=0xffffffff, signal=GDB_SIGNAL_DEFAULT) infrun: resume (step=0, signal=GDB_SIGNAL_0), trap_expected=0, current thread [Thread 1] at 0x40 infrun: infrun_async(1) infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait 720 infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait *** EXIT code 0 infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: -1.0.0 [Thread 0], infrun: status->kind = ignore infrun: TARGET_WAITKIND_IGNORE infrun: prepare_to_wait infrun: target_wait (-1.0.0, status) = infrun: 42000.0.0 [Remote target], infrun: status->kind = exited, status = 0 infrun: TARGET_WAITKIND_EXITED [Inferior 1 (Remote target) exited normally] infrun: stop_waiting infrun: clear_step_over_info I don't have a good fix for this at the moment, but it may be related to the fact that qemu doesn't report thread lists. It sounds like we shouldn't drop to the prompt while we wait for something to happen in all-stop mode either. Both runs above had target-non-stop off.