On Fri, Mar 4, 2022 at 9:14 AM Nathan Chancellor <nathan@xxxxxxxxxx> wrote: > > diff --git a/Documentation/kbuild/llvm.rst b/Documentation/kbuild/llvm.rst > index d32616891dcf..68b74416ec48 100644 > --- 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. I don't think we should do this; `PATH=/path/to/llvm/ make LLVM=1` works and (my interpretation of what) Masahiro said "if anyone asks for this, here's how we could do that." I don't think I've seen an explicit ask for that. I'd rather LLVM= have 2 behaviors than 3, but I won't hold this patch up over that. Either way: Reviewed-by: Nick Desaulniers <ndesaulniers@xxxxxxxxxx> > + > +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``. Hmm... I can see someone's build wrappers setting LLVM=1, then them being surprised that appending LLVM=0 doesn't disable LLVM=1 as they might expect. But Masahiro says let's fix this later which is fine. -- Thanks, ~Nick Desaulniers
