From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 1775 invoked by alias); 21 Sep 2017 16:01:02 -0000 Mailing-List: contact gdb-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: gdb-owner@sourceware.org Received: (qmail 1756 invoked by uid 89); 21 Sep 2017 16:01:02 -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,RP_MATCHES_RCVD,SPF_HELO_PASS,SPF_PASS autolearn=ham version=3.3.2 spammy=Sept X-Spam-User: qpsmtpd, 2 recipients X-HELO: smtp.polymtl.ca Received: from smtp.polymtl.ca (HELO smtp.polymtl.ca) (132.207.4.11) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with ESMTP; Thu, 21 Sep 2017 16:01:00 +0000 Received: from simark.ca (simark.ca [158.69.221.121]) (authenticated bits=0) by smtp.polymtl.ca (8.14.7/8.14.7) with ESMTP id v8LG0pOR027351 (version=TLSv1/SSLv3 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 21 Sep 2017 12:00:57 -0400 Received: by simark.ca (Postfix, from userid 112) id 825F01E517; Thu, 21 Sep 2017 12:00:51 -0400 (EDT) Received: from simark.ca (localhost [127.0.0.1]) by simark.ca (Postfix) with ESMTP id 7A6EA1E512; Thu, 21 Sep 2017 12:00:30 -0400 (EDT) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Date: Thu, 21 Sep 2017 16:01:00 -0000 From: Simon Marchi To: Petr Ovtchenkov Cc: Pedro Alves , Matt Rice , Fiodar Stryzhniou , Andreas Schwab , Binutils , Joel Brobecker , Matthias Klose , GDB Subject: Re: meaning of "Automatic date update in version.in" commits In-Reply-To: <20170921184615.6b1e5d44@void-ptr.info> References: <20170921135845.479dfc76@void-ptr.info> <024439c7-2083-d368-0138-2160e4494b81@redhat.com> <20170921152240.16bb4cc0@void-ptr.info> <8740f2a7-1300-3116-f34b-5487a8cd8b2b@redhat.com> <20170921161743.3ddc6bb9@void-ptr.info> <20170921184615.6b1e5d44@void-ptr.info> Message-ID: X-Sender: simon.marchi@polymtl.ca User-Agent: Roundcube Webmail/1.3.0 X-Poly-FromMTA: (simark.ca [158.69.221.121]) at Thu, 21 Sep 2017 16:00:51 +0000 X-IsSubscribed: yes X-SW-Source: 2017-09/txt/msg00081.txt.bz2 On 2017-09-21 17:46, Petr Ovtchenkov wrote: >> Binary reproducible builds mean that if you and I start with the same >> source code and same build tools, we will get exactly the same build >> artifacts. Here the build can't "depend on what date you use": > > If "date stamp" inserted into binary is a build date, It is definitely not a build date (as in the date at which you run make), I don't think anybody is suggesting that. > then we will have different > binaries. If we will use something else, for example "last commit" > date, > then we may have "same" build, but may not. From equality of "last > commit" date > not follow binary equivalence (consider cherry-picked commit, for > example, > or variations of sample "git diff 3110f4be18a2 f625a739" I show above). That's the part I don't understand in your reasoning. f625a739 is the commit that bumps the date to Sept 20 in the binutils-2_29-branch, 3110f4be18a2 is the commit that bumps the date to Sept 20 in the gdb-8.0-branch. They happen to have the same title and same diff, but they are otherwise not related. Those two branches do not contain the same code, and therefore are not expected to produce the same build artifacts. So if you checkout the repo at f625a739 (state at which the gdb 8.0 branch was on Sept 20) and I do the same, we'll be able to get reproducible builds if we use the same toolchain (unless something else entirely causes the build to not be reproducible, I haven't tried). Simon