linux-kernel - Re: [PATCH 4/4] kbuild: include Makefile.compiler only when compiler is required

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Date:   Sun, 28 Feb 2021 16:00:09 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>
Cc:     Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Israel Tsadok <itsadok@...il.com>
Subject: Re: [PATCH 4/4] kbuild: include Makefile.compiler only when compiler
 is required

On Sun, Feb 28, 2021 at 3:10 PM Masahiro Yamada <masahiroy@...nel.org> wrote:
>
> Since commit f2f02ebd8f38 ("kbuild: improve cc-option to clean up all
> temporary files"), running 'make kernelversion' in a read-only source
> tree emits a bunch of warnings:
>
>   mkdir: cannot create directory '.tmp_12345': Permission denied
>
> Non-build targets such as kernelversion, clean, help, etc. do not
> need to evaluate $(call cc-option,) and friends. Do not include
> Makefile.compiler so $(call cc-option,) becomes no-op.
>
> This not only fix the warnings, but also runs non-build targets much
> faster.
>
> Basically, all installation targets should also be non-build targets.
> Unfortunately, vdso_install requires the compiler because it builds
> vdso before installtion. This is a problem that must be fixed by a
> separate patch.
>
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
> ---
>
> I am not adding Reported-by for now because a reporter sent me
> an email privately.
>
> If he allows me to add Reported-by, I will add it to record
> the credit.
>
> (Perhaps, another person might have reported a similar issue
> somewhere, but my memory is obsure. I cannot recall it.)
>

Now, I got acknowledge to add this:

Reported-by: Israel Tsadok <itsadok@...il.com>







>  Makefile | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index eec7a94f5c33..20724711dc71 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -263,6 +263,10 @@ no-dot-config-targets := $(clean-targets) \
>                          $(version_h) headers headers_% archheaders archscripts \
>                          %asm-generic kernelversion %src-pkg dt_binding_check \
>                          outputmakefile
> +# Installation targets should not require compiler. Unfortunately, vdso_install
> +# is an exception where build artifacts may be updated. This must be fixed.
> +no-compiler-targets := $(no-dot-config-targets) install dtbs_install \
> +                       headers_install modules_install kernelrelease image_name
>  no-sync-config-targets := $(no-dot-config-targets) %install kernelrelease \
>                           image_name
>  single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
> @@ -270,6 +274,7 @@ single-targets := %.a %.i %.ko %.lds %.ll %.lst %.mod %.o %.s %.symtypes %/
>  config-build   :=
>  mixed-build    :=
>  need-config    := 1
> +need-compiler  := 1
>  may-sync-config        := 1
>  single-build   :=
>
> @@ -279,6 +284,12 @@ ifneq ($(filter $(no-dot-config-targets), $(MAKECMDGOALS)),)
>         endif
>  endif
>
> +ifneq ($(filter $(no-compiler-targets), $(MAKECMDGOALS)),)
> +       ifeq ($(filter-out $(no-compiler-targets), $(MAKECMDGOALS)),)
> +               need-compiler :=
> +       endif
> +endif
> +
>  ifneq ($(filter $(no-sync-config-targets), $(MAKECMDGOALS)),)
>         ifeq ($(filter-out $(no-sync-config-targets), $(MAKECMDGOALS)),)
>                 may-sync-config :=
> @@ -584,7 +595,9 @@ endif
>
>  # Include this also for config targets because some architectures need
>  # cc-cross-prefix to determine CROSS_COMPILE.
> +ifdef need-compiler
>  include $(srctree)/scripts/Makefile.compiler
> +endif
>
>  ifdef config-build
>  # ===========================================================================
> --
> 2.27.0
>


-- 
Best Regards
Masahiro Yamada