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=-19.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SPF_HELO_NONE,URIBL_BLOCKED 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 53ABCC07E95 for ; Tue, 20 Jul 2021 08:06:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 37AB3611C1 for ; Tue, 20 Jul 2021 08:06:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232464AbhGTHZl (ORCPT ); Tue, 20 Jul 2021 03:25:41 -0400 Received: from conssluserg-01.nifty.com ([210.131.2.80]:53274 "EHLO conssluserg-01.nifty.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232018AbhGTHZb (ORCPT ); Tue, 20 Jul 2021 03:25:31 -0400 Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) (authenticated) by conssluserg-01.nifty.com with ESMTP id 16K85aIU019345; Tue, 20 Jul 2021 17:05:36 +0900 DKIM-Filter: OpenDKIM Filter v2.10.3 conssluserg-01.nifty.com 16K85aIU019345 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nifty.com; s=dec2015msa; t=1626768336; bh=tW4cmCGAAsT+oeAelhZJnVPmEjCboZT3XEV//GSWizc=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=mrzdUsA3YIn+n3k708pPIjUMuCFNnG0zjwNEjS7NS0oRb+OPyxaowI79c4X9RKDYe efORXFgY4PEg490syeOUncMfUd28ikGQyEM3dIbQJSLXbnRy4RCM9lILXdM96K7RyQ 6y+Got5LjsSfvgvYSowHzlsg3a3bkn3PH6NN/ysXGUKCrwAufZXJL2rDxcO79qv5S4 vg2X6/wZx/UcEI56ODaVxuYZtmGenVCbKE13FOVjErZA1sTXF/qy61HTjtENgiCQIU oDQS/wxnLjIOT7OVLjNJAsDBOH4ATW3saP9AHWEGNb6TQiDs23RxcYaYTWBFQ0duKD 2FXaI2+DDcQCw== X-Nifty-SrcIP: [209.85.214.182] Received: by mail-pl1-f182.google.com with SMTP id d1so11080565plg.0; Tue, 20 Jul 2021 01:05:36 -0700 (PDT) X-Gm-Message-State: AOAM531TauQ6hVeSRSvvG3+jRMprMNvuY6Sf0gEWfDYpYmW2enetQiWf a9j9dstY3W5qvN8O1QPMfX0qvIoxyiAk1hLFjII= X-Google-Smtp-Source: ABdhPJzj3AbsPJOsaEQdbpIotcSzOv6la/CgbC2360JBxnvUghgVdl5W+6VGJWzqojG/auw+XBkC1CgStexuggsL8LY= X-Received: by 2002:a17:90a:c506:: with SMTP id k6mr34598471pjt.198.1626768335780; Tue, 20 Jul 2021 01:05:35 -0700 (PDT) MIME-Version: 1.0 References: <20210708232522.3118208-1-ndesaulniers@google.com> <20210708232522.3118208-3-ndesaulniers@google.com> In-Reply-To: <20210708232522.3118208-3-ndesaulniers@google.com> From: Masahiro Yamada Date: Tue, 20 Jul 2021 17:04:58 +0900 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCH v2 2/2] Makefile: infer CROSS_COMPILE from SRCARCH for LLVM=1 LLVM_IAS=1 To: Nick Desaulniers Cc: Miguel Ojeda , Fangrui Song , Michal Marek , Arnd Bergmann , Linux Kernel Mailing List , Linux Kbuild mailing list , clang-built-linux , Geert Uytterhoeven , Christoph Hellwig , Linus Torvalds , Nathan Chancellor Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jul 9, 2021 at 8:25 AM '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 > --- > 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),) Do you need to check $(LLVM) ? LLVM=1 is a convenient switch to change all the defaults, but yet you can flip each tool individually. Instead of LLVM=1, you still should be able to get the equivalent setups by: make CC=clang LD=ld.lld AR=llvm-ar OBJCOPY=llvm-objcopy ... The --target option is passed to only KBUILD_CFLAGS and KBUILD_AFLAGS. So, when we talk about --target=, we only care about whether $(CC) is Clang. Not caring about $(AR), $(LD), or $(OBJCOPY). scripts/Makefile.clang is already guarded by: ifneq ($(findstring clang,$(CC_VERSION_TEXT)), > +ifeq ($(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 > -- > 2.32.0.93.g670b81a890-goog > > -- > You received this message because you are subscribed to the Google Groups "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an email to clang-built-linux+unsubscribe@googlegroups.com. > To view this discussion on the web visit https://groups.google.com/d/msgid/clang-built-linux/20210708232522.3118208-3-ndesaulniers%40google.com. -- Best Regards Masahiro Yamada