From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.suse.de ([195.135.220.15]:36839 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753395AbcFGJiZ (ORCPT ); Tue, 7 Jun 2016 05:38:25 -0400 Subject: Re: Regression in "kbuild: fix if_change and friends to consider argument order" References: <1465263518.3885.9.camel@intel.com> From: Michal Marek Message-ID: <5756960E.5020706@suse.com> Date: Tue, 7 Jun 2016 11:38:22 +0200 MIME-Version: 1.0 In-Reply-To: <1465263518.3885.9.camel@intel.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kbuild-owner@vger.kernel.org List-ID: To: "Zanoni, Paulo R" , "yamada.masahiro@socionext.com" Cc: "linux-kbuild@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "nicolas.pitre@linaro.org" On 2016-06-07 03:38, Zanoni, Paulo R wrote: > Hi > > I recently noticed that alternating between "make" and "make targz-pkg" > rebuilds the whole Kernel. This was not happening before. As a Kernel > developer, my build/install/test environment heavily relies on the fact > that "make targz-pkg" only quickly generates the tarball if everything > is already built, so this change is heavily impacting my development > environment. > > I did some bisection and concluded that the first bad commit is: > > commit 9c8fa9bc08f60ac657751daba9fccf828a36cfed > Author: Masahiro Yamada > Date: Sat May 7 15:48:26 2016 +0900 > kbuild: fix if_change and friends to consider argument order > > I also verified that if I just revert this commit on top of the > most recent tree it goes back to the usual behavior. > > I read the commit message and it seems that some unneeded rebuilds are > somewhat expected, but I can't understand why such a change in the > command line like the one I did triggers everything to be rebuilt. > IMHO, it really shouldn't. I also wonder that maybe the regression I'm > experiencing was not expected in the original change, so maybe there's > a way to keep the original improvement caused by the mentioned patch > without the regression I'm experiencing. > > How to reproduce (exact commands I used at every bisect step): > > $ make tinyconfig > $ time make -j4 V=2 # this should build things > $ time make -j4 V=2 # just to make sure nothing will be rebuilt > $ time make -j4 V=2 targz-pkg I can reproduce it. Michal