lkml.org 
[lkml]   [2022]   [Mar]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
From
Date
SubjectRe: [PATCH v2] kbuild: Make $(LLVM) more flexible
On Fri, Mar 4, 2022 at 9:14 AM Nathan Chancellor <nathan@kernel.org> 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@google.com>

> +
> +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

\
 
 \ /
  Last update: 2022-03-07 20:10    [W:0.149 / U:0.360 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site