linux-kernel - Re: [PATCH] kbuild: use -fmacro-prefix-map for .S sources compilation

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Date:   Mon, 2 Nov 2020 20:16:55 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Denys Zagorui <dzagorui@...co.com>
Cc:     Michal Marek <michal.lkml@...kovi.net>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kbuild: use -fmacro-prefix-map for .S sources compilation

On Thu, Oct 29, 2020 at 8:22 PM Denys Zagorui <dzagorui@...co.com> wrote:
>
> Follow-up to a73619a845d5 ("kbuild: use -fmacro-prefix-map to make
> __FILE__ a relative path") commit. Assembler sources also use __FILE__
> macro so this flag should be also apllied to that sources.
>
> Signed-off-by: Denys Zagorui <dzagorui@...co.com>
> ---
>  Makefile | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/Makefile b/Makefile
> index ee2284a5cad2..26c4294f6e25 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -947,6 +947,7 @@ KBUILD_CFLAGS   += $(call cc-option,-Werror=designated-init)
>
>  # change __FILE__ to the relative path from the srctree
>  KBUILD_CFLAGS  += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)
> +KBUILD_AFLAGS  += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)



-fmacro-prefix-map is a preprocessor option.

https://gcc.gnu.org/onlinedocs/gcc-10.2.0/gcc/Preprocessor-Options.html#Preprocessor-Options



I think it makes more sense to replace

KBUILD_CFLAGS  += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)

with

KBUILD_CPPFLAGS        += $(call cc-option,-fmacro-prefix-map=$(srctree)/=)


Then, this flag will be passed to .S files as well as .c files.








>  # ensure -fcf-protection is disabled when using retpoline as it is
>  # incompatible with -mindirect-branch=thunk-extern
> --
> 2.19.0.dirty
>


--
Best Regards
Masahiro Yamada