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| author |   Nick Desaulniers <ndesaulniers@google.com> | 2021-08-06 10:27:01 -0700 |
|---|---|---|
| committer |   Masahiro Yamada <masahiroy@kernel.org> | 2021-08-10 09:13:25 +0900 |
| commit | f12b034afeb3a977bbb1c6584dedc0f3dc666f14 (patch) | |
| tree | 3f3a5d488e333bbde7c8b8a00caf05aad1163fb0 /Documentation/kbuild | |
| parent | kbuild: check CONFIG_AS_IS_LLVM instead of LLVM_IAS (diff) | |
| download | linux-dev-f12b034afeb3a977bbb1c6584dedc0f3dc666f14.tar.xz linux-dev-f12b034afeb3a977bbb1c6584dedc0f3dc666f14.zip | |
scripts/Makefile.clang: default to LLVM_IAS=1
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 <ndesaulniers@google.com>
Reviewed-by: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>
Diffstat (limited to 'Documentation/kbuild')
| -rw-r--r-- | Documentation/kbuild/llvm.rst | 14 |
1 files changed, 8 insertions, 6 deletions
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=<triple>``. -Unless ``LLVM_IAS=1`` is specified, ``CROSS_COMPILE`` is also used to derive -``--prefix=<path>`` to search for the GNU assembler and linker. - If ``CROSS_COMPILE`` is not specified, the ``--target=<triple>`` 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=<path>`` to search for the GNU assembler and linker. :: + + make ARCH=arm64 LLVM=1 LLVM_IAS=0 CROSS_COMPILE=aarch64-linux-gnu- Supported Architectures ----------------------- |