linux-kernel - Re: [PATCH 1/2] Makefile: Fix distcc compilation with x86 macros

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Message-ID: <20181113113000.GB4788@gmail.com>
Date:   Tue, 13 Nov 2018 12:30:00 +0100
From:   Ingo Molnar <mingo@...nel.org>
To:     Nadav Amit <namit@...are.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
        linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] Makefile: Fix distcc compilation with x86 macros


* Nadav Amit <namit@...are.com> wrote:

> Introducing the use of asm macros in c-code broke distcc, since it only
> sends the preprocessed source file. The solution is to break the
> compilation into two separate phases of compilation and assembly, and
> between the two concatanate the assembly macros and the compiled (yet

s/concatenate

> not assembled) source file. Since this is less efficient, this
> compilation mode is only used when make is called with the "DISTCC=y"
> parameter.
> 
> Note that the assembly stage should also be distributed, if distcc is
> configured using "CFLAGS=-DENABLE_REMOTE_ASSEMBLE".

It's a bit sad that we regressed distcc performance ...

> +# If distcc is used, then when an assembly macro files is needed, the
> +# compilation stage and the assembly stage need to be separated. Providing
> +# "DISTCC=y" option enables the separate compilation and assembly.

Let's fix the various typos:

  > +# If distcc is used, and when assembly macro files are needed, the
  > +# compilation stage and the assembly stage needs to be separated. 
  > +# Providing the "DISTCC=y" option enables separate compilation and 
  > +# assembly.



> +cmd_cc_o_c_direct = $(CC) $(c_flags) -c -o $(1) $<
> +
> +ifeq ($(DISTCC),y)
> +a_flags_no_debug = $(filter-out $(AFLAGS_DEBUG_INFO), $(a_flags))
> +c_flags_no_macros = $(filter-out $(ASM_MACRO_FLAGS), $(c_flags))
> +
> +cmd_cc_o_c_two_steps =							\
> +	$(CC) $(c_flags_no_macros) $(DISABLE_LTO) -fverbose-asm -S	\
> +		-o $(@D)/.$(@F:.o=.s) $< ;				\
> +	cat $(ASM_MACRO_FILE) $(@D)/.$(@F:.o=.s) >			\
> +		$(@D)/.tmp_$(@F:.o=.s);					\
> +	$(CC) $(a_flags_no_debug) -c -o $(1) $(@D)/.tmp_$(@F:.o=.s) ; 	\
> +	rm -f $(@D)/.$(@F:.o=.s) $(@D)/.tmp_$(@F:.o=.s)			\
> +
> +cmd_cc_o_c_helper =    							\
> +	$(if $(findstring $(ASM_MACRO_FLAGS),$(c_flags)),		\
> +		$(call cmd_cc_o_c_two_steps, $(1)),			\
> +		$(call cmd_cc_o_c_direct, $(1)))

There are various stray <space>+<tab> whitespace noise errors in the 
chunks above.

Thanks,

	Ingo