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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 34B21C433E0 for ; Fri, 29 May 2020 04:48:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 118EB20814 for ; Fri, 29 May 2020 04:48:30 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="g2oVffvD" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725914AbgE2Es3 (ORCPT ); Fri, 29 May 2020 00:48:29 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34898 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725601AbgE2Es1 (ORCPT ); Fri, 29 May 2020 00:48:27 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:e::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A15A5C08C5C6; Thu, 28 May 2020 21:48:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=Content-Transfer-Encoding: Content-Type:In-Reply-To:MIME-Version:Date:Message-ID:From:References:Cc:To: Subject:Sender:Reply-To:Content-ID:Content-Description; bh=vIdlsNk1thlgd2wJmYEsdZAcqlZDKs65gLXHa0aj9qw=; b=g2oVffvDUd+ewmKpTwyGrqdBQW m9Q42HUdyfcH5SEhjTGLhoAVvr/CzUpv4kaUeIUFckaTwsNhxtbtE3eEhlVUPjjG+zT07IjLyIVpa GMrSiqJuYtST3QVfTxnkTM7QmVym28LIPfGMmo0/EJf2bmeWKck1el+9a/0aWVpNOMgxA4mzSao7y 1MtjuUQ1cuCS+2QiNCu8HT8D0bq+sONjtS1do3wA/2nEFrt1y0gOPuxRf8SrhqXO0nGSb4JZUGHoR ZpNwcQ29YNw8qavBZgpRDCSFS4mqdV+eKb/fI9A2ISa9edrqsk2JXV5SVByg/CvzkxOA7GynRLNGV Gul9jxrg==; Received: from [2601:1c0:6280:3f0::19c2] by bombadil.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1jeWwP-0000he-7z; Fri, 29 May 2020 04:48:21 +0000 Subject: Re: next-20200528 - build error in kernel/rcu/refperf.c To: =?UTF-8?Q?Valdis_Kl=c4=93tnieks?= , "Paul E. McKenney" , Josh Triplett , Steven Rostedt Cc: rcu@vger.kernel.org, linux-kernel@vger.kernel.org References: <538911.1590725791@turing-police> From: Randy Dunlap Message-ID: <9d8b13db-9d77-416d-e283-9ea509ce43d1@infradead.org> Date: Thu, 28 May 2020 21:48:18 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: <538911.1590725791@turing-police> Content-Type: text/plain; charset=UTF-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 5/28/20 9:16 PM, Valdis Klētnieks wrote: > commit 9088b449814f788d24f35a5840b6b2c2a23cd32a > Author: Paul E. McKenney > Date: Mon May 25 17:22:24 2020 -0700 > > refperf: Provide module parameter to specify number of experiments > > changes this line of code (line 389) > > - reader_tasks[exp].result_avg = 1000 * process_durations(exp) / ((exp + 1) * loops); > + result_avg[exp] = 1000 * process_durations(nreaders) / (nreaders * loops); > > On a 32-bit ARM make allmodconfig with gcc 8.3, this results in: > > ERROR: modpost: "__aeabi_uldivmod" [kernel/rcu/refperf.ko] undefined! > make[1]: *** [scripts/Makefile.modpost:103: __modpost] Error 1 > > I admit not understanding why the original line of code worked and the new one doesn't. > Maybe gcc is smarter/dumber about the ranges of 'exp' and 'nreaders' than we thought? > Paul has already responded: (unfortunately) "So I am restricting to 64BIT for the time being. Yeah, I know, lazy of me. ;-)" https://lore.kernel.org/lkml/20200528180855.GP2869@paulmck-ThinkPad-P72/ -- ~Randy