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=-7.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham 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 AA144C433E0 for ; Fri, 22 May 2020 18:17:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 72DDC2072C for ; Fri, 22 May 2020 18:17:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1590171465; bh=5sm5AYmWV9mWrN3CXxji+zYrj9CAOWdQtOxPPpby3TQ=; h=References:In-Reply-To:From:Date:Subject:To:Cc:List-ID:From; b=XTzhC/o7NEiGQWLqJbb4F8HzZGtW+a10bDcG59C7za3kqzYS6CpHkCBVlSCQA0+ck 2hlUl6sW+F8K/ojXkVPK79iKvTIqEaD9Gg9qxKedKf8x3eOKRA9rn1Ph2L7wF82qLT +JFQq+DJmnnyoPcjO+FOq6koS91e+RhvhHYR9J8M= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730849AbgEVSRo (ORCPT ); Fri, 22 May 2020 14:17:44 -0400 Received: from conssluserg-01.nifty.com ([210.131.2.80]:27085 "EHLO conssluserg-01.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726373AbgEVSRo (ORCPT ); Fri, 22 May 2020 14:17:44 -0400 Received: from mail-vs1-f49.google.com (mail-vs1-f49.google.com [209.85.217.49]) (authenticated) by conssluserg-01.nifty.com with ESMTP id 04MIHPFT017391; Sat, 23 May 2020 03:17:26 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-01.nifty.com 04MIHPFT017391 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1590171446; bh=K3rGYVbuX5itC10Uy7MCO78NVqbVQ6AyydvbG4IPunc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=dhexHP4r5UqBuJyFcetL7gZMMeLBW26NawGnk14bzmlelLVztkIDN1E0gLMszC8iN LfNAqpZeYKV+IeNfOaLaqZvhSN3mqfXxrGu5xsfzdnHN5Zo6ZCY0xBV+wP/5n2E1JK KjVIkJSMIO8yTKTRjacARUmWXPShANGo/FvPtKiJ45Z/qz/o4G2zqbdaz0hm8NjcDJ lVVgK1Xfu8Kc4G8M12/SabtFxb8ZlMw0eyEF1uNRTe5iT31KoNOJVzAMEgwrt8HPq6 p0tfWgoGNNeKesnh5O7g9PBkxtcVthZrEZERBCLHkt+9bpTQmI/mZ1YZxgfQsYwon9 hkwaiuS8woBfA== X-Nifty-SrcIP: [209.85.217.49] Received: by mail-vs1-f49.google.com with SMTP id w65so6555458vsw.11; Fri, 22 May 2020 11:17:26 -0700 (PDT) X-Gm-Message-State: AOAM533oGn99TT1pavUP+Sf44Nf1QwSo/v0bJfEiVd8xSVYQKEH+aBHY 40ZrXEb0voCmCwmW+vL/gv+8yvHA00Wnhk1BVtQ= X-Google-Smtp-Source: ABdhPJyegX+5hSC8vQtFsfk2gsG8jhLEllAduD0C3D9DpxotRifsVoWTIhA0Kp06+8I7BRCrvI4FLB9S1OKqCcRKAk4= X-Received: by 2002:a05:6102:3231:: with SMTP id x17mr250058vsf.181.1590171445169; Fri, 22 May 2020 11:17:25 -0700 (PDT) MIME-Version: 1.0 References: <20200521202716.193316-1-samitolvanen@google.com> <202005211506.2700F86@keescook> In-Reply-To: <202005211506.2700F86@keescook> From: Masahiro Yamada Date: Sat, 23 May 2020 03:16:49 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH] kbuild: reuse vmlinux.o in vmlinux_link To: Kees Cook Cc: Sami Tolvanen , Michal Marek , Linux Kbuild mailing list , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 22, 2020 at 7:08 AM Kees Cook wrote: > > On Thu, May 21, 2020 at 01:27:16PM -0700, Sami Tolvanen wrote: > > Instead of linking all compilation units again each time vmlinux_link is > > called, reuse vmlinux.o from modpost_link. > > > > With x86_64 allyesconfig, vmlinux_link is called three times and reusing > > vmlinux.o reduces the build time ~38 seconds on my system (59% reduction > > in the time spent in vmlinux_link). > > Nice! Any time savings at final link is a big cumulative win. > > > Signed-off-by: Sami Tolvanen > > --- > > scripts/link-vmlinux.sh | 5 +---- > > 1 file changed, 1 insertion(+), 4 deletions(-) > > > > diff --git a/scripts/link-vmlinux.sh b/scripts/link-vmlinux.sh > > index d09ab4afbda4..c6cc4305950c 100755 > > --- a/scripts/link-vmlinux.sh > > +++ b/scripts/link-vmlinux.sh > > @@ -77,11 +77,8 @@ vmlinux_link() > > > > if [ "${SRCARCH}" != "um" ]; then > > objects="--whole-archive \ > > - ${KBUILD_VMLINUX_OBJS} \ > > + vmlinux.o \ > > --no-whole-archive \ > > - --start-group \ > > - ${KBUILD_VMLINUX_LIBS} \ > > - --end-group \ > > ${@}" > > > > ${LD} ${KBUILD_LDFLAGS} ${LDFLAGS_vmlinux} \ > > I think the "um" case can be updated as well too, yes? I agree. I changed the um part, then ARCH=um build is successful. > Also, I think the comment above modpost_link() needs to be updated now > to reflect the nature of how vmlinux.o gets used after this patch. > > -- > Kees Cook -- Best Regards Masahiro Yamada