From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.freebsd.org (mx2.freebsd.org [IPv6:2610:1c1:1:606c::19:2]) by sourceware.org (Postfix) with ESMTPS id A16A93858D35 for ; Wed, 8 Jul 2020 00:35:11 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org A16A93858D35 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=FreeBSD.org Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=jhb@FreeBSD.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) client-signature RSA-PSS (4096 bits)) (Client CN "mx1.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx2.freebsd.org (Postfix) with ESMTPS id EE73C97D5F; Wed, 8 Jul 2020 00:35:07 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from smtp.freebsd.org (smtp.freebsd.org [96.47.72.83]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "smtp.freebsd.org", Issuer "Let's Encrypt Authority X3" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4B1gLg5Lcyz4JNb; Wed, 8 Jul 2020 00:35:07 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Received: from John-Baldwins-MacBook-Pro-274.local (unknown [IPv6:2601:648:8203:2990:98ed:1435:28a2:b475]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client did not present a certificate) (Authenticated sender: jhb) by smtp.freebsd.org (Postfix) with ESMTPSA id 46D131202A; Wed, 8 Jul 2020 00:35:07 +0000 (UTC) (envelope-from jhb@FreeBSD.org) Subject: Re: Multiprocess on FreeBSD From: John Baldwin To: Pedro Alves , gdb-patches@sourceware.org References: <20200414175434.8047-1-palves@redhat.com> <935bd7c8-f107-f2d1-ade2-f6259dc1297c@FreeBSD.org> Autocrypt: addr=jhb@FreeBSD.org; keydata= mQGiBETQ+XcRBADMFybiq69u+fJRy/0wzqTNS8jFfWaBTs5/OfcV7wWezVmf9sgwn8TW0Dk0 c9MBl0pz+H01dA2ZSGZ5fXlmFIsee1WEzqeJzpiwd/pejPgSzXB9ijbLHZ2/E0jhGBcVy5Yo /Tw5+U/+laeYKu2xb0XPvM0zMNls1ah5OnP9a6Ql6wCgupaoMySb7DXm2LHD1Z9jTsHcAQMD /1jzh2BoHriy/Q2s4KzzjVp/mQO5DSm2z14BvbQRcXU48oAosHA1u3Wrov6LfPY+0U1tG47X 1BGfnQH+rNAaH0livoSBQ0IPI/8WfIW7ub4qV6HYwWKVqkDkqwcpmGNDbz3gfaDht6nsie5Z pcuCcul4M9CW7Md6zzyvktjnbz61BADGDCopfZC4of0Z3Ka0u8Wik6UJOuqShBt1WcFS8ya1 oB4rc4tXfSHyMF63aPUBMxHR5DXeH+EO2edoSwViDMqWk1jTnYza51rbGY+pebLQOVOxAY7k do5Ordl3wklBPMVEPWoZ61SdbcjhHVwaC5zfiskcxj5wwXd2E9qYlBqRg7QeSm9obiBCYWxk d2luIDxqaGJARnJlZUJTRC5vcmc+iGAEExECACAFAkTQ+awCGwMGCwkIBwMCBBUCCAMEFgID AQIeAQIXgAAKCRBy3lIGd+N/BI6RAJ9S97fvbME+3hxzE3JUyUZ6vTewDACdE1stFuSfqMvM jomvZdYxIYyTUpC5Ag0ERND5ghAIAPwsO0B7BL+bz8sLlLoQktGxXwXQfS5cInvL17Dsgnr3 1AKa94j9EnXQyPEj7u0d+LmEe6CGEGDh1OcGFTMVrof2ZzkSy4+FkZwMKJpTiqeaShMh+Goj XlwIMDxyADYvBIg3eN5YdFKaPQpfgSqhT+7El7w+wSZZD8pPQuLAnie5iz9C8iKy4/cMSOrH YUK/tO+Nhw8Jjlw94Ik0T80iEhI2t+XBVjwdfjbq3HrJ0ehqdBwukyeJRYKmbn298KOFQVHO EVbHA4rF/37jzaMadK43FgJ0SAhPPF5l4l89z5oPu0b/+5e2inA3b8J3iGZxywjM+Csq1tqz hltEc7Q+E08AAwUIAL+15XH8bPbjNJdVyg2CMl10JNW2wWg2Q6qdljeaRqeR6zFus7EZTwtX sNzs5bP8y51PSUDJbeiy2RNCNKWFMndM22TZnk3GNG45nQd4OwYK0RZVrikalmJY5Q6m7Z16 4yrZgIXFdKj2t8F+x613/SJW1lIr9/bDp4U9tw0V1g3l2dFtD3p3ZrQ3hpoDtoK70ioIAjjH aIXIAcm3FGZFXy503DOA0KaTWwvOVdYCFLm3zWuSOmrX/GsEc7ovasOWwjPn878qVjbUKWwx Q4QkF4OhUV9zPtf9tDSAZ3x7QSwoKbCoRCZ/xbyTUPyQ1VvNy/mYrBcYlzHodsaqUDjHuW+I SQQYEQIACQUCRND5ggIbDAAKCRBy3lIGd+N/BCO8AJ9j1dWVQWxw/YdTbEyrRKOY8YZNwwCf afMAg8QvmOWnHx3wl8WslCaXaE8= Message-ID: <36435498-0c12-7e2b-3bbe-8e965ce7c80b@FreeBSD.org> Date: Tue, 7 Jul 2020 17:34:05 -0700 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.12; rv:68.0) Gecko/20100101 Thunderbird/68.6.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, KAM_DMARC_STATUS, RCVD_IN_DNSWL_LOW, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gdb-patches@sourceware.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gdb-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 08 Jul 2020 00:35:12 -0000 On 7/7/20 5:10 PM, John Baldwin wrote: > On 7/7/20 4:16 PM, John Baldwin wrote: >> FNAT: stop for LWP 101641 event 1 flags 0x18 >> FLWP: fbsd_resume for ptid (70453, 101518, 0) >> >> Program terminated with signal SIGTRAP, Trace/breakpoint trap. >> The program no longer exists. >> >> Here you can see that the last call to fbsd_resume() used the ptid from >> inferior 1 instead of inferior 2, and inferior 1 didn't discard it's >> pending SIGTRAP but instead was killed by it.) > > On this part, I turned on 'set debug infrun 1' and can see that > the core is trying to step over the breakpoint in the first > inferior. However, it is not clearing the SIGTRAP signal to > GDB_SIGNAL_0 when resuming the first inferior but leaving it as > GDB_SIGNAL_TRAP. This appears to be because start_step_over() > calls keep_going_pass_signal() instead of keep_going(), so > tp->control.stop_signal doesn't get reset. I'm not sure if > stop_signal should have been cleared earlier somehow? > > Hmm, if I add a hack to ignore SIGTRAP in fbsd_nat_target::resume(), > then what happens is that the first inferior runs to completion. > I can run the second inferior after switching to it, but I think the > behavior I probably want is for the core to not resume threads from > the non-current inferior instead? > > One last test I tried is to do this sequence instead in the first > inferior: > > (gdb) file /bin/ls > (gdb) start > (gdb) n > > This gets the first inferior off of the breakpoint and the thread is > stopped for a hardware stepping trap instead. > > I can then add an inferior do start and have it work fine, and I > can switch back and forth between the two inferiors stepping each > one. > > So I think the issue here is that for some reason when the 'start' > command for inferior 2 tries to resume the inferior after getting > across the initial events for exec, it ends up resuming the wrong > inferior due to confusion about the thread stopped at a breakpoint. > However, it doesn't get confused if the thread is stopped for some > other reason. I had to add a 'fbsd_nat_target::supports_multi_process' method and now it seems to work fine. It does depend on the fix to use find_inferior_pid() to work. -- John Baldwin