kbuild: Make $(LLVM) more flexible

[linux-2.6-microblaze.git] / Documentation / kbuild / llvm.rst

diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst
index d326168..b854bb4 100644 (file)
--- a/Documentation/kbuild/llvm.rst
+++ b/Documentation/kbuild/llvm.rst
@@ -49,17 +49,36 @@ example: ::
 LLVM Utilities
 --------------
 
-LLVM has substitutes for GNU binutils utilities. Kbuild supports ``LLVM=1``
-to enable them. ::
-
-       make LLVM=1
-
-They can be enabled individually. The full list of the parameters: ::
+LLVM has substitutes for GNU binutils utilities. They can be enabled individually.
+The full list of supported make variables::
 
        make CC=clang LD=ld.lld AR=llvm-ar NM=llvm-nm STRIP=llvm-strip \
          OBJCOPY=llvm-objcopy OBJDUMP=llvm-objdump READELF=llvm-readelf \
          HOSTCC=clang HOSTCXX=clang++ HOSTAR=llvm-ar HOSTLD=ld.lld
 
+To simplify the above command, Kbuild supports the ``LLVM`` variable::
+
+       make LLVM=1
+
+If your LLVM tools are not available in your PATH, you can supply their
+location using the LLVM variable with a trailing slash::
+
+       make LLVM=/path/to/llvm/
+
+which will use ``/path/to/llvm/clang``, ``/path/to/llvm/ld.lld``, etc.
+
+If your LLVM tools have a version suffix and you want to test with that
+explicit version rather than the unsuffixed executables like ``LLVM=1``, you
+can pass the suffix using the ``LLVM`` variable::
+
+       make LLVM=-14
+
+which will use ``clang-14``, ``ld.lld-14``, etc.
+
+``LLVM=0`` is not the same as omitting ``LLVM`` altogether, it will behave like
+``LLVM=1``. If you only wish to use certain LLVM utilities, use their respective
+make variables.
+
 The integrated assembler is enabled by default. You can pass ``LLVM_IAS=0`` to
 disable it.