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=-13.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT 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 84363C43381 for ; Tue, 2 Apr 2019 07:27:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F3C620830 for ; Tue, 2 Apr 2019 07:27:33 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="jVTc/8d1" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729312AbfDBH1c (ORCPT ); Tue, 2 Apr 2019 03:27:32 -0400 Received: from mail-ed1-f66.google.com ([209.85.208.66]:39065 "EHLO mail-ed1-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727498AbfDBH1b (ORCPT ); Tue, 2 Apr 2019 03:27:31 -0400 Received: by mail-ed1-f66.google.com with SMTP id p20so10674421eds.6; Tue, 02 Apr 2019 00:27:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=cA/b/nkb9WBsfSOKUo8nbbc8KTipOuDl/05pH+iF1oo=; b=jVTc/8d17VTNrLO2Dk86ssaQym/gPPCsnIA+MCcDcchkvg6H9zVNNY1EVKrwC+BtmC xRGImDgvjco8T0olMXsQGxBnr4vqL54aL+UcjagndBaoxJG3kDozCL8TStm7fbQkZvr4 zEZKBOeKOmdV1EgR5Fn+GR5trc3NRp1N/JyKB2hOmWqd0pBSt6laws5qHOBTU1QNxvyB Zv2pE0HF7SvhCfxF5d+OdLF6nZzJxsXzfbI+I8MVfb0cco+xNJAEyQ6YioQQqD9UPNOQ x9704Q1eribYncIUNFkOSFIZ9xxIdVYUvnh8e3lCNwAeqCv9ejC6IJM+MmKBpM0Wzg6u YUGg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=cA/b/nkb9WBsfSOKUo8nbbc8KTipOuDl/05pH+iF1oo=; b=PrpG8jJOb4b0SOp1K8JX4u357wKjbDTAAIHhPdI5MzggnAjYW2NcFhMkDS/fiMqNDr o2TkuKOc9vCr+8nw87lr28ipYoRReugK1t23jXWmC+3SGN79FkMd618yT1lTUWsiV6M8 2qgyD2YRmXnS77/BjDsExtFfAPcKOjnYUmuxDhQTxTLPNZrIUv6NDfHCY41qQw1GMaJ7 7EdOnr4QAz7zqFw4BHoX7EtKF2yd2p+GTU4TeAFw6LE1KgTKQ40qLUTrT1/T4XsmyxoK mcas+6kGEbNfAfD6svD+7oLGWstJiaquF/o5NmlZMHP7fUA9gzNSj0ggGWv9tFArw8Sq m0fA== X-Gm-Message-State: APjAAAU2w3dSqn8rpXkR6D/en8kyd9AYImGJbXjlLXE2/2YWuKdr9RFO Isl5bczrXUjVxTjzGB7gmPY= X-Google-Smtp-Source: APXvYqwcW17r6fDydot9+EbPSSdp4AwJXkferdClP8DKrtzE4YzVPSN9JBudDci3PUWvqz3kbIZrlg== X-Received: by 2002:a17:906:3db1:: with SMTP id y17mr11907370ejh.90.1554190049433; Tue, 02 Apr 2019 00:27:29 -0700 (PDT) Received: from archlinux-ryzen ([2a01:4f9:2a:1fae::2]) by smtp.gmail.com with ESMTPSA id j3sm2298229ejv.22.2019.04.02.00.27.28 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 02 Apr 2019 00:27:28 -0700 (PDT) Date: Tue, 2 Apr 2019 00:27:26 -0700 From: Nathan Chancellor To: Nick Desaulniers Cc: yamada.masahiro@socionext.com, keescook@chromium.org, clang-built-linux@googlegroups.com, Michal Marek , linux-kbuild@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v3] Makefile: lld: tell clang to use lld Message-ID: <20190402072726.GA16650@archlinux-ryzen> References: <20190402070858.49597-1-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190402070858.49597-1-ndesaulniers@google.com> User-Agent: Mutt/1.11.4 (2019-03-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 02, 2019 at 12:08:58AM -0700, Nick Desaulniers wrote: > This is needed because clang doesn't select which linker to use based on > $LD but rather -fuse-ld={bfd,gold,lld,}. This > is problematic especially for cc-ldoption, which checks for linker flag > support via invoking the compiler, rather than the linker. > > Select the linker via absolute path from $PATH via `which`. This allows > you to build with: > > $ make LD=ld.lld > $ make LD=ld.lld-8 > $ make LD=/path/to/ld.lld > > Add -Qunused-arguments to KBUILD_CPPFLAGS when using LLD, as otherwise > Clang likes to complain about -fuse-lld= being unused when compiling but > not linking (-c) such as when cc-option is used. > > Link: https://github.com/ClangBuiltLinux/linux/issues/342 > Link: https://github.com/ClangBuiltLinux/linux/issues/366 > Link: https://github.com/ClangBuiltLinux/linux/issues/357 > Suggested-by: Nathan Chancellor > Suggested-by: Masahiro Yamada > Signed-off-by: Nick Desaulniers > --- > Changes V2->V3: > * Use absolute path based on `which $LD` as per Masahiro. > * Add -Qunused-arguments. > * Drop tested-by/reviewed-by tags, since this patched has changed enough > to warrant re-testing/re-review, IMO. > * Add more info to the commit message. > Changes V1->V2: > * add reviewed and tested by tags. > * move this addition up 2 statments so that it's properly added to > KBUILD_*FLAGS as per Nathan. > > Makefile | 4 ++++ > 1 file changed, 4 insertions(+) > > diff --git a/Makefile b/Makefile > index 026fbc450906..895c076b6305 100644 > --- a/Makefile > +++ b/Makefile > @@ -514,6 +514,10 @@ ifneq ($(GCC_TOOLCHAIN),) > CLANG_FLAGS += --gcc-toolchain=$(GCC_TOOLCHAIN) > endif > CLANG_FLAGS += -no-integrated-as > +ifneq ($(shell $(LD) --version 2>&1 | head -n 1 | grep LLD),) > +CLANG_FLAGS += -fuse-ld=$(shell which $(LD)) > +KBUILD_CPPFLAGS += -Qunused-arguments We should remove the -Qunused-arguments call in the second clang block at the same time. With that change: Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor > +endif > KBUILD_CFLAGS += $(CLANG_FLAGS) > KBUILD_AFLAGS += $(CLANG_FLAGS) > export CLANG_FLAGS > -- > 2.21.0.392.gf8f6787159e-goog >