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=-23.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 autolearn=unavailable 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 E8DA2C07E9B for ; Fri, 9 Jul 2021 20:44:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C3A51613BC for ; Fri, 9 Jul 2021 20:44:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229854AbhGIUq4 (ORCPT ); Fri, 9 Jul 2021 16:46:56 -0400 Received: from mail.kernel.org ([198.145.29.99]:41080 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229506AbhGIUqz (ORCPT ); Fri, 9 Jul 2021 16:46:55 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 00ADB613B2; Fri, 9 Jul 2021 20:44:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1625863451; bh=CQ1uaoyjJxIqi5KhvkuC3UnaAu1VcgMADpeocbtDAQM=; h=Subject:To:Cc:References:From:Date:In-Reply-To:From; b=qPTyyP4rMGxwAfln56HZ+XI48oPphnsEb01PmcQC5Xn1eLhZIPhsoGyhrSfqub1bI 91GOsmWA1d7UNOMjtQRW1dcKSqXhrvWz1antqN3+ZktA5jOZiPt35qaPfSODNagGHu ygNyDlUDiErvlPZWqci69IqgzJQ7tRXICKYYXVHZsY2+JnMgHlcFCsHqMU0+ShmD+8 g65r1duNkKCFLDOhizJZnW9Ib2NKTmNoKT7Bgqfka8A+Y5WBfR1WmKdnL0/E/PEECS AZLboic1uZy/yW79CDhfKsVKcBemxvEUwoxu8nZnnVlsbyYF1pcK8GAOo6kJMQ8ibR D55E6qVk+VDdA== Subject: Re: [PATCH v2 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for LLVM=1 LLVM_IAS=1 To: Nick Desaulniers , Masahiro Yamada Cc: Miguel Ojeda , Fangrui Song , Michal Marek , Arnd Bergmann , linux-kernel@vger.kernel.org, linux-kbuild@vger.kernel.org, clang-built-linux@googlegroups.com, Geert Uytterhoeven , Christoph Hellwig , Linus Torvalds References: <20210708232522.3118208-1-ndesaulniers@google.com> <20210708232522.3118208-3-ndesaulniers@google.com> From: Nathan Chancellor Message-ID: Date: Fri, 9 Jul 2021 13:44:10 -0700 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.11.0 MIME-Version: 1.0 In-Reply-To: <20210708232522.3118208-3-ndesaulniers@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/8/2021 4:25 PM, 'Nick Desaulniers' via Clang Built Linux wrote: > We get constant feedback that the command line invocation of make is too > long. CROSS_COMPILE is helpful when a toolchain has a prefix of the > target triple, or is an absolute path outside of $PATH, but it's mostly > redundant for a given SRCARCH. SRCARCH itself is derived from ARCH > (normalized for a few different targets). > > If CROSS_COMPILE is not set, simply set --target= for CLANG_FLAGS, > KBUILD_CFLAGS, and KBUILD_AFLAGS based on $SRCARCH. > > Previously, we'd cross compile via: > $ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make LLVM=1 LLVM_IAS=1 > Now: > $ ARCH=arm64 make LLVM=1 LLVM_IAS=1 > > For native builds (not involving cross compilation) we now explicitly > specify a target triple rather than rely on the implicit host triple. > > Link: https://github.com/ClangBuiltLinux/linux/issues/1399 > Suggested-by: Arnd Bergmann > Suggested-by: Nathan Chancellor > Suggested-by: Masahiro Yamada > Signed-off-by: Nick Desaulniers I tested arm, arm64, i386, riscv, and x86_64 and verified that the error fired for an unsupported arch. Consider this: Reviewed-by: Nathan Chancellor Tested-by: Nathan Chancellor > --- > Changes v1 -> v2: > * Fix typos in commit message as per Geert and Masahiro. > * Use SRCARCH instead of ARCH, simplifying x86 handling, as per > Masahiro. Add his sugguested by tag. > * change commit oneline from 'drop' to 'infer.' > * Add detail about explicit host --target and relationship of ARCH to > SRCARCH, as per Masahiro. > > Changes RFC -> v1: > * Rebase onto linux-kbuild/for-next > * Keep full target triples since missing the gnueabi suffix messes up > 32b ARM. Drop Fangrui's sugguested by tag. Update commit message to > drop references to arm64. > * Flush out TODOS. > * Add note about -EL/-EB, -m32/-m64. > * Add note to Documentation/. > > Documentation/kbuild/llvm.rst | 5 +++++ > scripts/Makefile.clang | 34 ++++++++++++++++++++++++++++++++-- > 2 files changed, 37 insertions(+), 2 deletions(-) > > diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst > index b18401d2ba82..80c63dd9a6d1 100644 > --- a/Documentation/kbuild/llvm.rst > +++ b/Documentation/kbuild/llvm.rst > @@ -46,6 +46,11 @@ example: :: > > clang --target=aarch64-linux-gnu foo.c > > +When both ``LLVM=1`` and ``LLVM_IAS=1`` are used, ``CROSS_COMPILE`` becomes > +unnecessary and can be inferred from ``ARCH``. Example: :: > + > + ARCH=arm64 make LLVM=1 LLVM_IAS=1 > + > LLVM Utilities > -------------- > > diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang > index 297932e973d4..956603f56724 100644 > --- a/scripts/Makefile.clang > +++ b/scripts/Makefile.clang > @@ -1,6 +1,36 @@ > -ifneq ($(CROSS_COMPILE),) > +# Individual arch/{arch}/Makfiles should use -EL/-EB to set intended endianness > +# and -m32/-m64 to set word size based on Kconfigs instead of relying on the > +# target triple. > +ifeq ($(CROSS_COMPILE),) > +ifneq ($(LLVM),) > +ifeq ($(LLVM_IAS),1) > +ifeq ($(SRCARCH),arm) > +CLANG_FLAGS += --target=arm-linux-gnueabi > +else ifeq ($(SRCARCH),arm64) > +CLANG_FLAGS += --target=aarch64-linux-gnu > +else ifeq ($(SRCARCH),hexagon) > +CLANG_FLAGS += --target=hexagon-linux-gnu > +else ifeq ($(SRCARCH),m68k) > +CLANG_FLAGS += --target=m68k-linux-gnu > +else ifeq ($(SRCARCH),mips) > +CLANG_FLAGS += --target=mipsel-linux-gnu > +else ifeq ($(SRCARCH),powerpc) > +CLANG_FLAGS += --target=powerpc64le-linux-gnu > +else ifeq ($(SRCARCH),riscv) > +CLANG_FLAGS += --target=riscv64-linux-gnu > +else ifeq ($(SRCARCH),s390) > +CLANG_FLAGS += --target=s390x-linux-gnu > +else ifeq ($(SRCARCH),x86) > +CLANG_FLAGS += --target=x86_64-linux-gnu > +else > +$(error Specify CROSS_COMPILE or add '--target=' option to scripts/Makefile.clang) > +endif # SRCARCH > +endif # LLVM_IAS > +endif # LLVM > +else > CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) > -endif > +endif # CROSS_COMPILE > + > ifeq ($(LLVM_IAS),1) > CLANG_FLAGS += -integrated-as > else >