From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 13714 invoked by alias); 2 Mar 2018 20:09:08 -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 13681 invoked by uid 89); 2 Mar 2018 20:09:08 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,SPF_PASS autolearn=ham version=3.3.2 spammy=charge X-HELO: 9pmail.ess.barracuda.com Received: from 9pmail.ess.barracuda.com (HELO 9pmail.ess.barracuda.com) (64.235.150.225) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Fri, 02 Mar 2018 20:09:07 +0000 Received: from MIPSMAIL01.mipstec.com (mailrelay.mips.com [12.201.5.28]) by mx29.ess.sfj.cudaops.com (version=TLSv1.2 cipher=ECDHE-RSA-AES256-SHA384 bits=256 verify=NO); Fri, 02 Mar 2018 20:09:02 +0000 Received: from [10.20.78.177] (10.20.78.177) by mips01.mipstec.com (10.20.43.31) with Microsoft SMTP Server id 14.3.361.1; Fri, 2 Mar 2018 11:32:00 -0800 Date: Fri, 02 Mar 2018 20:09:00 -0000 From: "Maciej W. Rozycki" To: John Baldwin CC: Subject: Re: [PATCH] Workaround a FreeBSD ptrace() bug with clearing thread events. In-Reply-To: <1908872.BAzsX71dkG@ralph.baldwin.cx> Message-ID: References: <20180224000935.43344-1-jhb@FreeBSD.org> <1908872.BAzsX71dkG@ralph.baldwin.cx> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" X-BESS-ID: 1520021342-637139-10611-413079-1 X-BESS-VER: 2018.2-r1802232356 X-BESS-Apparent-Source-IP: 12.201.5.28 X-BESS-Outbound-Spam-Score: 0.00 X-BESS-Outbound-Spam-Report: Code version 3.2, rules version 3.2.2.190610 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------- 0.00 BSF_BESS_OUTBOUND META: BESS Outbound X-BESS-Outbound-Spam-Status: SCORE=0.00 using account:ESS59374 scores of KILL_LEVEL=7.0 tests=BSF_BESS_OUTBOUND X-BESS-BRTS-Status:1 X-SW-Source: 2018-03/txt/msg00069.txt.bz2 On Fri, 2 Mar 2018, John Baldwin wrote: > > Hmm, doesn't it have to be a run-time check then? Otherwise you're > > basing your decision on the host system GDB has been built for and not one > > it will be run on, which I suppose does not necessarily have to be of the > > same version. Or am I missing anything here? > > FreeBSD generally does not support forwards-compatability for binaries (newer > binary on older kernel), only backwards-compatability (older binary on newer > kernel). In this case, using the workaround is also fine on a fixed kernel, > so it doesn't hurt if GDB is compiled on an older system (thus using the > workaround) and then run under a newer kernel. Fair enough. Is the one-way compatibility enforced though, by a system library runtime or the kernel somehow, by refusing to run a binary built for a kernel that is newer than one currently in charge of the system? Otherwise the rule would be quite fragile and error prone, asking for extra care to be taken by the user. Maciej