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a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=DsQFy/CzTnQXNoNOJwZLuGXsmdWykdOYnmIA1IAJYnI=; b=efiQgJcheuKJ2i/3h4Nx9BT/yPj7zIiMg1KzfAptDupjnjb3EaOYZGZYzxVvgxMct+ jmKNnJfraxKZsddn1zbprU1lYQhwFpi3LxxO1zr23rWY+NxmFkigpkBsc3gsfJuN3VWR 4GvfDeqspoaJPYAJtI74ehAu6iJUWIMIrlRPYM977rRfwoiYcsS90kO9zo2iAvLE2/39 pktLoNWSVMmknqPqGRi5sDn6jN7vRQTfKE/SpYSmaYMeUd5OZ2S9zt4UYe2RoU4EP/SY s5b86F5DwHv1za1HBPd7oXtAkUZfICBFGy53OykfNg6t4RQETBgF+3Zhdp/tXdzKGIbt d/hQ== X-Gm-Message-State: AOAM530r3dJ8ZtjH3zr7AvF2usELpaHXwdZ5NPYUS5iWdo3of/7DjevG 1fN4AG95naEnFS+1/8Vc0LZQ8UTH2yrAaAccx2c= X-Google-Smtp-Source: ABdhPJxlVebXFVl1DX68O2az9jnUDVOkZsun/wYx/gJq/Ne5YY7RqIBz45lXfXNMiZy//yphthHXxKGwM9UXhBISE9s= X-Received: from ndesaulniers1.mtv.corp.google.com ([2620:15c:211:202:d20b:bb87:51cd:edc3]) (user=ndesaulniers job=sendgmr) by 2002:a05:6214:27e4:: with SMTP id jt4mr1006501qvb.45.1628270826503; Fri, 06 Aug 2021 10:27:06 -0700 (PDT) Date: Fri, 6 Aug 2021 10:27:01 -0700 Message-Id: <20210806172701.3993843-1-ndesaulniers@google.com> Mime-Version: 1.0 X-Mailer: git-send-email 2.32.0.605.g8dce9f2422-goog Subject: [PATCH v2] scripts/Makefile.clang: default to LLVM_IAS=1 From: Nick Desaulniers To: Masahiro Yamada , Nathan Chancellor Cc: Khem Raj , Matthew Wilcox , Nick Desaulniers , Michal Marek , Jonathan Corbet , Paul Walmsley , Palmer Dabbelt , Albert Ou , clang-built-linux@googlegroups.com, linux-kbuild@vger.kernel.org, linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-riscv@lists.infradead.org X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20210806_102709_344906_23F76B59 X-CRM114-Status: GOOD ( 11.58 ) X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org LLVM_IAS=1 controls enabling clang's integrated assembler via -integrated-as. This was an explicit opt in until we could enable assembler support in Clang for more architecures. Now we have support and CI coverage of LLVM_IAS=1 for all architecures except a few more bugs affecting s390 and powerpc. This commit flips the default from opt in via LLVM_IAS=1 to opt out via LLVM_IAS=0. CI systems or developers that were previously doing builds with CC=clang or LLVM=1 without explicitly setting LLVM_IAS must now explicitly opt out via LLVM_IAS=0, otherwise they will be implicitly opted-in. This finally shortens the command line invocation when cross compiling with LLVM to simply: $ make ARCH=arm64 LLVM=1 Signed-off-by: Nick Desaulniers Reviewed-by: Nathan Chancellor --- Changes v1 -> v2: * Drop "Currently" from Documentation/, as per Matthew. * Drop Makefile and riscv Makefile, rebase on https://lore.kernel.org/lkml/20210805150102.131008-1-masahiroy@kernel.org/ as per Masahiro. * Base is kbuild/for-next, plus https://lore.kernel.org/lkml/20210802183910.1802120-1-ndesaulniers@google.com/ https://lore.kernel.org/lkml/20210805150102.131008-1-masahiroy@kernel.org/. Documentation/kbuild/llvm.rst | 14 ++++++++------ scripts/Makefile.clang | 6 +++--- 2 files changed, 11 insertions(+), 9 deletions(-) base-commit: d7a86429dbc691bf540688fcc8542cc20246a85b prerequisite-patch-id: 0d3072ecb5fd06ff6fd6ea81fe601f6c54c23910 prerequisite-patch-id: 2654829756eb8a094a0ffad1679caa75a4d86619 prerequisite-patch-id: a51e7885ca2376d008bbf146a5589da247806f7b prerequisite-patch-id: 6a0342755115ec459610657edac1075f069faa3d diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst index f8a360958f4c..e87ed5479963 100644 --- a/Documentation/kbuild/llvm.rst +++ b/Documentation/kbuild/llvm.rst @@ -60,17 +60,14 @@ They can be enabled individually. The full list of the parameters: :: OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \ HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld -Currently, the integrated assembler is disabled by default. You can pass -``LLVM_IAS=1`` to enable it. +The integrated assembler is enabled by default. You can pass ``LLVM_IAS=0`` to +disable it. Omitting CROSS_COMPILE ---------------------- As explained above, ``CROSS_COMPILE`` is used to set ``--target=``. -Unless ``LLVM_IAS=1`` is specified, ``CROSS_COMPILE`` is also used to derive -``--prefix=`` to search for the GNU assembler and linker. - If ``CROSS_COMPILE`` is not specified, the ``--target=`` is inferred from ``ARCH``. @@ -78,7 +75,12 @@ That means if you use only LLVM tools, ``CROSS_COMPILE`` becomes unnecessary. For example, to cross-compile the arm64 kernel:: - make ARCH=arm64 LLVM=1 LLVM_IAS=1 + make ARCH=arm64 LLVM=1 + +If ``LLVM_IAS=0`` is specified, ``CROSS_COMPILE`` is also used to derive +``--prefix=`` to search for the GNU assembler and linker. :: + + make ARCH=arm64 LLVM=1 LLVM_IAS=0 CROSS_COMPILE=aarch64-linux-gnu- Supported Architectures ----------------------- diff --git a/scripts/Makefile.clang b/scripts/Makefile.clang index 1f4e3eb70f88..3ae63bd35582 100644 --- a/scripts/Makefile.clang +++ b/scripts/Makefile.clang @@ -22,12 +22,12 @@ else CLANG_FLAGS += --target=$(notdir $(CROSS_COMPILE:%-=%)) endif # CROSS_COMPILE -ifeq ($(LLVM_IAS),1) -CLANG_FLAGS += -integrated-as -else +ifeq ($(LLVM_IAS),0) CLANG_FLAGS += -no-integrated-as GCC_TOOLCHAIN_DIR := $(dir $(shell which $(CROSS_COMPILE)elfedit)) CLANG_FLAGS += --prefix=$(GCC_TOOLCHAIN_DIR)$(notdir $(CROSS_COMPILE)) +else +CLANG_FLAGS += -integrated-as endif CLANG_FLAGS += -Werror=unknown-warning-option KBUILD_CFLAGS += $(CLANG_FLAGS)