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,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 8FDAFC43381 for ; Tue, 2 Apr 2019 07:57:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 563D220830 for ; Tue, 2 Apr 2019 07:57:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="sMeK5+uF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729160AbfDBH5b (ORCPT ); Tue, 2 Apr 2019 03:57:31 -0400 Received: from mail-ed1-f68.google.com ([209.85.208.68]:36964 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726905AbfDBH5a (ORCPT ); Tue, 2 Apr 2019 03:57:30 -0400 Received: by mail-ed1-f68.google.com with SMTP id v21so10753667edq.4; Tue, 02 Apr 2019 00:57:29 -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=PDzEI0LQqgCaaBXpu0DLpU1NfxthO6DRHjU6wR4TtN0=; b=sMeK5+uFBAH4RgqVbDkmOZkOjjEvvYDjvo6BZgUeNLC8AVBVNs9svJnjFgZ/fgk7aK mGstoTJOLVjJeouinwulk/oiYTjYdNuwEitHx9gwNX3ItIbuPCr+hcYdY07i5/xze8au 3UzPwFr0NEwWWREle1fgCm1SpkBsN3odBfNHUmsMQgfftdWmXZpP9BZ5evdhb1/Ktd0H bSU9L+WaOhnNqGA83F7ohiKCg8YOegzkXWpywsB8ZRrLWqTH70eXVD0Fq0yq8GGOn665 Q9WuZQZtkgITBP0U1VJssXkceV5o3IoJPV/kD22shbZzX3hILD/MuBsKfj7+ApP/LPcf xqmg== 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=PDzEI0LQqgCaaBXpu0DLpU1NfxthO6DRHjU6wR4TtN0=; b=kLRz9Vb3CY1CxipJTbQBdEgl4w7aJThJnLWou8ztFirN4sw0JP+7RpPVVLNJToCBQ+ VNc2DqfDbGaZBB9AAQQPDrAQvILNEsLO9MjnZ6z4mJ678sDY56OWUr1LoXfVC44n9wK+ /y6cVmgdGuvp2Ji5V5aylg0WyPFkK5JmS72oe2EIY2UWFyBpOV/jp++oC/wAJpPO3ka/ WWCKJ4+enuM6hah7xEns95D3MsO2k/iEP24Az76qdCALxrUMNIoCeqF9hUvju3ERu/qu hvI5bAaT3Urw2gdwqsMsX3y+dM6FqGaSsbyjXooefJcsei8CLMzqnkjsig4rDtW0j4c8 +Szw== X-Gm-Message-State: APjAAAUaBT4yC2mZfqCmF67u72ynSM5WnqsfiaCwFDyMWoBnYR/c/LAu 6fYGoyyMxmpnLHyfXHpOjD8= X-Google-Smtp-Source: APXvYqw4yVYKwYKTFDlMuvh7LK03/xq1y7OpcGD4StoG5pVUMv9EUefMw5NfIEFQyh9vsqT8fFI6aA== X-Received: by 2002:a50:8854:: with SMTP id c20mr45440137edc.167.1554191848380; Tue, 02 Apr 2019 00:57:28 -0700 (PDT) Received: from archlinux-ryzen ([2a01:4f9:2a:1fae::2]) by smtp.gmail.com with ESMTPSA id l20sm2300124ejb.30.2019.04.02.00.57.27 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Tue, 02 Apr 2019 00:57:27 -0700 (PDT) Date: Tue, 2 Apr 2019 00:57:25 -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 v4] Makefile: lld: tell clang to use lld Message-ID: <20190402075725.GB5308@archlinux-ryzen> References: <20190402072726.GA16650@archlinux-ryzen> <20190402073317.56529-1-ndesaulniers@google.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190402073317.56529-1-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 12:33:17AM -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 sooner, as otherwise > Clang likes to complain about -fuse-lld= being unused when compiling but > not linking (-c) such as when cc-option is used. There's no need to > guard with cc-option. > > 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 Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor > --- > Changes V3->V4: > * Unconditionally add -Qunused-arguments sooners, as per Nathan. > * Slight modification to commit message for that point. > Changes V2->V3: > * Use absolute path based on `which $LD` as per Masahiro. > * Add -Qunused-arguments. > * Drop tested-by/reviewed-by tags, since this patched has changed enough > to warrant re-testing/re-review, IMO. > * Add more info to the commit message. > Changes V1->V2: > * add reviewed and tested by tags. > * move this addition up 2 statments so that it's properly added to > KBUILD_*FLAGS as per Nathan. > > Makefile | 5 ++++- > 1 file changed, 4 insertions(+), 1 deletion(-) > > diff --git a/Makefile b/Makefile > index 026fbc450906..b290e76e1ca5 100644 > --- a/Makefile > +++ b/Makefile > @@ -514,6 +514,10 @@ ifneq ($(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)) > +endif > +KBUILD_CPPFLAGS += -Qunused-arguments > KBUILD_CFLAGS += $(CLANG_FLAGS) > KBUILD_AFLAGS += $(CLANG_FLAGS) > export CLANG_FLAGS > @@ -716,7 +720,6 @@ stackp-flags-$(CONFIG_STACKPROTECTOR_STRONG) := -fstack-protector-strong > KBUILD_CFLAGS += $(stackp-flags-y) > > ifdef CONFIG_CC_IS_CLANG > -KBUILD_CPPFLAGS += $(call cc-option,-Qunused-arguments,) > KBUILD_CFLAGS += $(call cc-disable-warning, format-invalid-specifier) > KBUILD_CFLAGS += $(call cc-disable-warning, gnu) > KBUILD_CFLAGS += $(call cc-disable-warning, address-of-packed-member) > -- > 2.21.0.392.gf8f6787159e-goog >