From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_2 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E547DC4338F for ; Mon, 23 Aug 2021 22:06:50 +0000 (UTC) Received: from smtp1.osuosl.org (smtp1.osuosl.org [140.211.166.138]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 236BD61183 for ; Mon, 23 Aug 2021 22:06:50 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 236BD61183 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=bootlin.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=busybox.net Received: from localhost (localhost [127.0.0.1]) by smtp1.osuosl.org (Postfix) with ESMTP id E69C280F81; Mon, 23 Aug 2021 22:06:49 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp1.osuosl.org ([127.0.0.1]) by localhost (smtp1.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Fh8_K-Sj1jbi; Mon, 23 Aug 2021 22:06:46 +0000 (UTC) Received: from ash.osuosl.org (ash.osuosl.org [140.211.166.34]) by smtp1.osuosl.org (Postfix) with ESMTP id 3A04280F82; Mon, 23 Aug 2021 22:06:45 +0000 (UTC) Received: from smtp4.osuosl.org (smtp4.osuosl.org [140.211.166.137]) by ash.osuosl.org (Postfix) with ESMTP id 219D21BF2F7 for ; Mon, 23 Aug 2021 22:06:44 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by smtp4.osuosl.org (Postfix) with ESMTP id 1E46E403B4 for ; Mon, 23 Aug 2021 22:06:44 +0000 (UTC) X-Virus-Scanned: amavisd-new at osuosl.org Received: from smtp4.osuosl.org ([127.0.0.1]) by localhost (smtp4.osuosl.org [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id kNwVzyRROoJK for ; Mon, 23 Aug 2021 22:06:39 +0000 (UTC) X-Greylist: domain auto-whitelisted by SQLgrey-1.8.0 Received: from relay12.mail.gandi.net (relay12.mail.gandi.net [217.70.178.232]) by smtp4.osuosl.org (Postfix) with ESMTPS id 77B94402E9 for ; Mon, 23 Aug 2021 22:06:39 +0000 (UTC) Received: (Authenticated sender: thomas.petazzoni@bootlin.com) by relay12.mail.gandi.net (Postfix) with ESMTPSA id 67D3C200003; Mon, 23 Aug 2021 22:06:35 +0000 (UTC) Date: Tue, 24 Aug 2021 00:06:34 +0200 From: Thomas Petazzoni To: Arnout Vandecappelle Message-ID: <20210824000634.07d68905@windsurf> In-Reply-To: References: <20210818065730.330904074D@smtp4.osuosl.org> <20210818122511.005d6a5c@windsurf> <20210818110558.GY27036@scaer> <20210818221842.5926641d@windsurf> <20210818210431.GZ27036@scaer> Organization: Bootlin X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Subject: Re: [Buildroot] [autobuild.buildroot.net] Daily results for 2021-08-17 X-BeenThere: buildroot@busybox.net X-Mailman-Version: 2.1.29 Precedence: list List-Id: Discussion and development of buildroot List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: "Yann E. MORIN" , buildroot@buildroot.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: buildroot-bounces@busybox.net Sender: "buildroot" Hello, On Mon, 23 Aug 2021 22:55:30 +0200 Arnout Vandecappelle wrote: > I have a theory, but it's a bit far out... We basically have this: > > gcc -o empty empty.c > objcopy --dump-section .interp=/dev/stdout empty > loader.txt > > The timestamp of 'empty' is going to be near the end of the gcc run. The > timestamp of 'loader.txt', on the other hand, is going to be all the way at the > beginning of the shell run. So, if the filesystem doesn't have nanosecond > precision, it's possible that 'empty' and 'loader.txt' have the same timestamp. > > It's not a good theory, though, because make shouldn't consider 'loader.txt' > older than 'empty' if they have exactly the same timestamp. > > > > Ooh, I just discovered something nasty! Apparently, objcopy updates the > modification time of its input file... > > $ touch empty; ls -l --full-time empty loader.txt; make SHARED=yes loader.txt; > ls -l --full-time empty loader.txt > -rwxr-xr-x 1 arnout arnout 24K 2021-08-23 22:53:27.450172624 +0200 empty* > -rw-r--r-- 1 arnout arnout 28 2021-08-23 22:52:57.949935937 +0200 loader.txt > objcopy --dump-section .interp=/dev/stdout empty > loader.txt > -rwxr-xr-x 1 arnout arnout 24K 2021-08-23 22:53:27.563173530 +0200 empty* > -rw-r--r-- 1 arnout arnout 28 2021-08-23 22:53:27.563173530 +0200 loader.txt > > I guess this way there is some chance that loader.txt gets a modification time > just before the updated mtime of empty... > > So the solution would be to touch loader.txt just after creating it. We could > patch it like that, give it a go in the autobuilders, then send the patch upstream? Wow, great investigation! Really odd that objcopy updates the mtime of its input file, though. Thomas -- Thomas Petazzoni, co-owner and CEO, Bootlin Embedded Linux and Kernel engineering https://bootlin.com _______________________________________________ buildroot mailing list buildroot@busybox.net http://lists.busybox.net/mailman/listinfo/buildroot