Commit 5ef87263 authored by Masahiro Yamada's avatar Masahiro Yamada
Browse files

kbuild: get rid of misleading $(AS) from documents 



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 v5.2, 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: default avatarMasahiro Yamada <yamada.masahiro@socionext.com>
Reviewed-by: default avatarNathan Chancellor <natechancellor@gmail.com>
parent 8e2442a5

Documentation/kbuild/kbuild.rst

+2 −3
Original line number Diff line number Diff line
@@ -38,12 +38,11 @@ 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

-------

Documentation/kbuild/makefiles.rst

+6 −6
Original line number Diff line number Diff line
@@ -328,7 +328,7 @@ 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::
@@ -489,7 +489,7 @@ 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
@@ -905,7 +905,7 @@ When kbuild executes, the following steps are followed (roughly): 
	vmlinux. The usage of $(call if_changed,xxx) will be described later.



    KBUILD_AFLAGS

	$(AS) assembler flags

	Assembler flags



	Default value - see top level Makefile

	Append or modify as required per architecture.
@@ -948,16 +948,16 @@ When kbuild executes, the following steps are followed (roughly): 
	to 'y' when selected.



    KBUILD_AFLAGS_KERNEL

	$(AS) options specific for built-in

	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

	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).

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