From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS3215 2.6.0.0/16 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A, RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by dcvr.yhbt.net (Postfix) with ESMTP id A39631F8C4 for ; Thu, 24 Mar 2022 12:56:17 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350333AbiCXM5r (ORCPT ); Thu, 24 Mar 2022 08:57:47 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46258 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350331AbiCXM5q (ORCPT ); Thu, 24 Mar 2022 08:57:46 -0400 Received: from frasgout.his.huawei.com (frasgout.his.huawei.com [185.176.79.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1E7F36E2A8 for ; Thu, 24 Mar 2022 05:56:14 -0700 (PDT) Received: from fraeml703-chm.china.huawei.com (unknown [172.18.147.207]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4KPQCl2NR6z67xwN; Thu, 24 Mar 2022 20:54:27 +0800 (CST) Received: from lhreml724-chm.china.huawei.com (10.201.108.75) by fraeml703-chm.china.huawei.com (10.206.15.52) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.2375.24; Thu, 24 Mar 2022 13:56:11 +0100 Received: from [10.202.227.197] (10.202.227.197) by lhreml724-chm.china.huawei.com (10.201.108.75) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2308.21; Thu, 24 Mar 2022 12:56:10 +0000 Message-ID: Date: Thu, 24 Mar 2022 12:56:32 +0000 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.6.1 Subject: Re: [Question] .git folder file updates for changing head commit To: Taylor Blau CC: References: <6fa76f28-063b-8964-c0a2-642dae88f1b3@huawei.com> From: John Garry In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.197] X-ClientProxiedBy: lhreml744-chm.china.huawei.com (10.201.108.194) To lhreml724-chm.china.huawei.com (10.201.108.75) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On 23/03/2022 20:25, Taylor Blau wrote: > On Wed, Mar 23, 2022 at 03:19:06PM +0000, John Garry wrote: >> For building the linux perf tool we use the git head commit id as part of >> the tool version sting. To save time in re-building, the Makefile rule has a >> dependency on .git/HEAD for rebuilding. An alternative approach would be to >> compare git log output to check current versus previous build head commit, >> but that is seen as inefficient time-wise. > Having a Makefile recipe that depends on $GIT_DIR/HEAD seems strange to > me. > Yeah, as mentioned, the idea was the we can check a rebuild on this rather than running a relatively time-consuming command like "git describe". Wasn't my idea :) > Presumably your Makefile rules would map out which parts of your program > depend on each other, and would get invalidated when the source itself > changes, no? Correct, they do. It's just the part which constructs the app version tag which depends on this. > > Perhaps you also care about the commit you're building from in order to > embed something into your program. But it seems like you could inject > the output of "git rev-parse HEAD" when you construct the version > identifier whenever you do need to rebuild. > ok, so I think that we may need to run a git command always one way or another. Thanks, John