From patchwork Tue Feb 13 07:08:55 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Cao jin X-Patchwork-Id: 10215253 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 8386F60467 for ; Tue, 13 Feb 2018 07:09:30 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7398528E45 for ; Tue, 13 Feb 2018 07:09:30 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 683AD28E4A; Tue, 13 Feb 2018 07:09:30 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C985328E45 for ; Tue, 13 Feb 2018 07:09:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933426AbeBMHJ3 (ORCPT ); Tue, 13 Feb 2018 02:09:29 -0500 Received: from mail.cn.fujitsu.com ([183.91.158.132]:5279 "EHLO heian.cn.fujitsu.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S933366AbeBMHJ2 (ORCPT ); Tue, 13 Feb 2018 02:09:28 -0500 X-IronPort-AV: E=Sophos;i="5.43,368,1503331200"; d="scan'208";a="37022158" Received: from bogon (HELO cn.fujitsu.com) ([10.167.33.5]) by heian.cn.fujitsu.com with ESMTP; 13 Feb 2018 15:09:26 +0800 Received: from G08CNEXCHPEKD02.g08.fujitsu.local (unknown [10.167.33.83]) by cn.fujitsu.com (Postfix) with ESMTP id 8A9E848AE761; Tue, 13 Feb 2018 15:09:25 +0800 (CST) Received: from [10.167.226.60] (10.167.226.60) by G08CNEXCHPEKD02.g08.fujitsu.local (10.167.33.89) with Microsoft SMTP Server (TLS) id 14.3.361.1; Tue, 13 Feb 2018 15:09:23 +0800 Subject: Re: why scripts/link-vmlinux.sh has a final build of init/ To: Masahiro Yamada CC: Michal Marek , Linux Kbuild mailing list , "linux-kernel@vger.kernel.org" References: From: Cao jin Message-ID: <6f19ae3f-249e-2d20-dcd6-e34c475a2638@cn.fujitsu.com> Date: Tue, 13 Feb 2018 15:08:55 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.4.0 MIME-Version: 1.0 In-Reply-To: Content-Language: en-US X-Originating-IP: [10.167.226.60] X-yoursite-MailScanner-ID: 8A9E848AE761.A88B1 X-yoursite-MailScanner: Found to be clean X-yoursite-MailScanner-From: caoj.fnst@cn.fujitsu.com Sender: linux-kbuild-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kbuild@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP On 02/12/2018 10:48 PM, Masahiro Yamada wrote: > 2018-02-12 13:22 GMT+09:00 Cao jin : >> Hi Masahiro-san, >> >> As I remember, init/ is already built during recursive make, and I did >> a clean build(make mrproper, make localmodconfig) with all plugins >> included on x86_64 with following patch, the kernel can boot without any >> obvious problem. So, I don't figure out why we need this final build? >> >> >> diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh >> index e6818b8e7141..086b2efd4d53 100755 >> --- a/scripts/link-vmlinux.sh >> +++ b/scripts/link-vmlinux.sh >> @@ -247,9 +247,6 @@ else >> expr 0$(cat .old_version) + 1 >.version; >> fi; >> >> -# final build of init/ >> -${MAKE} -f "${srctree}/scripts/Makefile.build" obj=init >> GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}" >> - >> archive_builtin >> >> #link vmlinux.o >> > > > link-vmlinux.sh increments '.version' > so it must descend into init/ > to update include/generated/compile.h > and re-compile init/version.o > > We do not increment '.version' > at the first descend into init/ > because we never know whether the kernel > is updated or not before the final link stage. > Oh, I wasn't aware of this process, now understood. Thanks Masahiro-san. BTW, I still have 2 questions. 1. In final build, why need    GCC_PLUGINS_CFLAGS="${GCC_PLUGINS_CFLAGS}" Doesn't GCC_PLUGINS_CFLAGS already exist in the environment? I also tested the Randomizing Structure Layout plugin with this patch, the plugin seems works in my test. 2. scripts/link-vmlinux.sh seems just handle only one argument: clean. So why shouldn't it be: vmlinux: scripts/link-vmlinux.sh vmlinux_prereq $(vmlinux-deps) FORCE diff --git a/Makefile b/Makefile index ccd981892ef2..21d93b545381 100644 --- a/Makefile +++ b/Makefile @@ -998,7 +998,7 @@ ARCH_POSTLINK := $(wildcard $(srctree)/arch/$(SRCARCH)/Makefile.postlink) # Final link of vmlinux with optional arch pass after final link cmd_link-vmlinux = \ - $(CONFIG_SHELL) $< $(LD) $(LDFLAGS) $(LDFLAGS_vmlinux) ; \ + $(CONFIG_SHELL) $<; \ $(if $(ARCH_POSTLINK), $(MAKE) -f $(ARCH_POSTLINK) $@, true)