On Fri, Jun 28, 2019 at 11:06 AM Masahiro Yamada
<yamada.masahiro@xxxxxxxxxxxxx> wrote:
>
> The assembler files in the kernel are *.S instead of *.s, so they must
> be preprocessed. Hence, we always use $(CC) as an assembler driver.
>
> $(AS) is almost unused in Kbuild. As of writing, there is just one user.
>
> $ git grep '$(AS)' -- :^Documentation
> drivers/net/wan/Makefile: AS68K = $(AS)
In Makefile, a variable is also referenced in a curly brace form like ${AS}.
In shell scripts, it can be referenced in the form of $AR.
I grepped more patterns.
$ git grep -e '$(AS)' -e '${AS}' -e '$AS' -e '$(AS:' -e '${AS:' --
:^Documentation
drivers/net/wan/Makefile: AS68K = $(AS)
I found only user still.
> The documentation about *_AFLAGS* sounds like the flags were passed
> to $(AS). This is somewhat misleading since we do not invoke $(AS)
> directly.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx>
> ---
>
> Documentation/kbuild/kbuild.txt | 5 ++---
> Documentation/kbuild/makefiles.txt | 12 ++++++------
> 2 files changed, 8 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
> index 9c230ea71963..7a7e2aa2fab5 100644
> --- a/Documentation/kbuild/kbuild.txt
> +++ b/Documentation/kbuild/kbuild.txt
> @@ -31,12 +31,11 @@ Additional options to the assembler (for built-in and modules).
>
> AFLAGS_MODULE
> --------------------------------------------------
> -Additional module specific options to use for $(AS).
> +Additional module specific options to use for assembler.
>
> AFLAGS_KERNEL
> --------------------------------------------------
> -Additional options for $(AS) when used for assembler
> -code for code that is compiled as built-in.
> +Additional options when used for assembling code that is compiled as built-in.
>
> KCFLAGS
> --------------------------------------------------
> diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
> index d65ad5746f94..f0b3a30b985d 100644
> --- a/Documentation/kbuild/makefiles.txt
> +++ b/Documentation/kbuild/makefiles.txt
> @@ -306,7 +306,7 @@ more details, with real examples.
> variable $(KBUILD_CFLAGS) and uses it for compilation flags for the
> entire tree.
>
> - asflags-y specifies options for assembling with $(AS).
> + asflags-y specifies options for assembling.
>
> Example:
> #arch/sparc/kernel/Makefile
> @@ -441,7 +441,7 @@ more details, with real examples.
> as-instr checks if the assembler reports a specific instruction
> and then outputs either option1 or option2
> C escapes are supported in the test instruction
> - Note: as-instr-option uses KBUILD_AFLAGS for $(AS) options
> + Note: as-instr-option uses KBUILD_AFLAGS for assembler options
>
> cc-option
> cc-option is used to check if $(CC) supports a given option, and if
> @@ -814,7 +814,7 @@ When kbuild executes, the following steps are followed (roughly):
> In this example, the binary $(obj)/image is a binary version of
> vmlinux. The usage of $(call if_changed,xxx) will be described later.
>
> - KBUILD_AFLAGS $(AS) assembler flags
> + KBUILD_AFLAGS assembler flags
>
> Default value - see top level Makefile
> Append or modify as required per architecture.
> @@ -853,15 +853,15 @@ When kbuild executes, the following steps are followed (roughly):
> The first example utilises the trick that a config option expands
> to 'y' when selected.
>
> - KBUILD_AFLAGS_KERNEL $(AS) options specific for built-in
> + KBUILD_AFLAGS_KERNEL assembler options specific for built-in
>
> $(KBUILD_AFLAGS_KERNEL) contains extra C compiler flags used to compile
> resident kernel code.
>
> - KBUILD_AFLAGS_MODULE Options for $(AS) when building modules
> + KBUILD_AFLAGS_MODULE Options for assembler when building modules
>
> $(KBUILD_AFLAGS_MODULE) is used to add arch-specific options that
> - are used for $(AS).
> + are used for assembler.
> From commandline AFLAGS_MODULE shall be used (see kbuild.txt).
>
> KBUILD_CFLAGS_KERNEL $(CC) options specific for built-in
> --
> 2.17.1
>
--
Best Regards
Masahiro Yamada
