From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 36600 invoked by alias); 30 Mar 2016 14:17:20 -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 36573 invoked by uid 89); 30 Mar 2016 14:17:19 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-1.9 required=5.0 tests=BAYES_00,KAM_LAZY_DOMAIN_SECURITY,RP_MATCHES_RCVD,SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=assurance, 77, rationale, posts X-HELO: mx1.redhat.com Received: from mx1.redhat.com (HELO mx1.redhat.com) (209.132.183.28) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES256-GCM-SHA384 encrypted) ESMTPS; Wed, 30 Mar 2016 14:17:13 +0000 Received: from int-mx13.intmail.prod.int.phx2.redhat.com (int-mx13.intmail.prod.int.phx2.redhat.com [10.5.11.26]) by mx1.redhat.com (Postfix) with ESMTPS id 9BD591E38 for ; Wed, 30 Mar 2016 14:17:12 +0000 (UTC) Received: from [127.0.0.1] (ovpn01.gateway.prod.ext.phx2.redhat.com [10.5.9.1]) by int-mx13.intmail.prod.int.phx2.redhat.com (8.14.4/8.14.4) with ESMTP id u2UEHBlv028409; Wed, 30 Mar 2016 10:17:11 -0400 Subject: Re: [patchv2 2/2] Workaround gdbserver<7.7 for setfs To: Jan Kratochvil References: <20160319201842.GA16540@host1.jankratochvil.net> <56F13963.9040204@redhat.com> <20160322131604.GA24312@host1.jankratochvil.net> <56F14F1E.5010606@redhat.com> <20160323211547.GA17400@host1.jankratochvil.net> <20160324220933.GA27445@host1.jankratochvil.net> <20160324223241.GB2548@host1.jankratochvil.net> Cc: gdb-patches@sourceware.org, Gary Benson From: Pedro Alves Message-ID: <56FBDFE7.90203@redhat.com> Date: Wed, 30 Mar 2016 14:17:00 -0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.7.1 MIME-Version: 1.0 In-Reply-To: <20160324223241.GB2548@host1.jankratochvil.net> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit X-SW-Source: 2016-03/txt/msg00562.txt.bz2 On 03/24/2016 10:32 PM, Jan Kratochvil wrote: > There was a bug in patchv1. > > > move2.patch > Please include self-contained a commit/rationale along with patch posts (and reposts). You had context in your intro to v1 that was lost in v2. > > gdb/ChangeLog > 2016-03-24 Jan Kratochvil > > * remote.c (packet_ok): Add workaround for PACKET_vFile_setfs. > > diff --git a/gdb/remote.c b/gdb/remote.c > index bb027cf..f80fee8 100644 > --- a/gdb/remote.c > +++ b/gdb/remote.c > @@ -1453,7 +1453,15 @@ packet_ok (const char *buf, struct packet_config *config) > internal_error (__FILE__, __LINE__, > _("packet_ok: attempt to use a disabled packet")); > > - result = packet_check_result (buf); > + if (config == &remote_protocol_packets[PACKET_vFile_setfs] > + && strcmp (buf, "OK") == 0) > + { > + /* Workaround gdbserver < 7.7 before its fix from 2013-12-11. */ > + result = PACKET_UNKNOWN; > + } This comment could use more detail. E.g., reading this I'm left wondering, did it always respond OK to unknown vFile packets, or to all unknown packets? I think it was actually the latter. AFAICS from the commit you pointed at in v1, the "OK" was gdbserver mistaking any unknown packet for a vStopped packet, with vStopped being the notification ack for the "%Stop" RSP async notification. So it could also happen that gdb sends the setfs packet while gdbserver had a pending notification, and then gdbserver replies back a stop reply instead of "OK"... We may need to guarantee an early enough setfs is attempted. Is that already the case? If I'm right and gdbserver mishandled _any_ unknown packet, then I wonder whether you fix this one, but will trip on another when you get past initial connection and actually do any serious debugging? If not, this may be sufficient. Otherwise, we may need to come up with a different workaround, maybe based on sending an early probe packet, like "MustReplyEmpty", to which well behaved stubs reply empty, just because that's not a known packet to them. If a stub replies something other than empty to that one, then maybe we should disable all other auto-probed packets... That may force-disable too much functionality though... So in sum: - Expand comment a bit / include commit log with rationale in the patch. - Give assurance that this is sufficient and that we won't trip on the same thing with other packets anyway. Otherwise we may need to think of something else. Thanks, Pedro Alves