| Message ID | 20190706162508.8529-1-yamada.masahiro@socionext.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v2] kbuild: get rid of misleading $(AS) from documents | expand |
On Sun, 7 Jul 2019 01:25:08 +0900 Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > The assembler files in the kernel are *.S instead of *.s, so they must > be preprocessed. Since 'as' of GNU binutils is not able to preprocess, > we always use $(CC) as an assembler driver. > > $(AS) is almost unused in Kbuild. As of writing, there is just one place > that directly invokes $(AS). > > $ git grep -e '$(AS)' -e '${AS}' -e '$AS' -e '$(AS:' -e '${AS:' -- :^Documentation > drivers/net/wan/Makefile: AS68K = $(AS) > > The documentation about *_AFLAGS* sounds like the flags were passed > to $(AS). This is somewhat misleading. > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> Would you like me to send this up through the docs tree? Thanks, jon
On Tue, Jul 9, 2019 at 5:02 AM Jonathan Corbet <corbet@lwn.net> wrote: > > On Sun, 7 Jul 2019 01:25:08 +0900 > Masahiro Yamada <yamada.masahiro@socionext.com> wrote: > > > The assembler files in the kernel are *.S instead of *.s, so they must > > be preprocessed. Since 'as' of GNU binutils is not able to preprocess, > > we always use $(CC) as an assembler driver. > > > > $(AS) is almost unused in Kbuild. As of writing, there is just one place > > that directly invokes $(AS). > > > > $ git grep -e '$(AS)' -e '${AS}' -e '$AS' -e '$(AS:' -e '${AS:' -- :^Documentation > > drivers/net/wan/Makefile: AS68K = $(AS) > > > > The documentation about *_AFLAGS* sounds like the flags were passed > > to $(AS). This is somewhat misleading. > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> > > Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> > > Would you like me to send this up through the docs tree? No, I will apply it to linux-kbuild shortly. Thanks.
diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt index 9c230ea71963..2c6188abb213 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 assembler options for modules. AFLAGS_KERNEL -------------------------------------------------- -Additional options for $(AS) when used for assembler -code for code that is compiled as built-in. +Additional assembler options for built-in. KCFLAGS -------------------------------------------------- diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt index d65ad5746f94..895bbbf38a0c 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 assembler options. 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 Assembler options specific for 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
The assembler files in the kernel are *.S instead of *.s, so they must be preprocessed. Since 'as' of GNU binutils is not able to preprocess, we always use $(CC) as an assembler driver. $(AS) is almost unused in Kbuild. As of writing, there is just one place that directly invokes $(AS). $ git grep -e '$(AS)' -e '${AS}' -e '$AS' -e '$(AS:' -e '${AS:' -- :^Documentation drivers/net/wan/Makefile: AS68K = $(AS) The documentation about *_AFLAGS* sounds like the flags were passed to $(AS). This is somewhat misleading. Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com> Reviewed-by: Nathan Chancellor <natechancellor@gmail.com> --- Changes in v2: - Rephrase without using "assembling" Documentation/kbuild/kbuild.txt | 5 ++--- Documentation/kbuild/makefiles.txt | 12 ++++++------ 2 files changed, 8 insertions(+), 9 deletions(-)