linux-kernel - Re: [PATCH v3 00/12] kbuild/kconfig: do not update config during installation

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Message-ID: <gh36wr1g0d.fsf@lena.gouders.net>
Date:   Tue, 10 Jul 2018 13:34:10 +0200
From:   Dirk Gouders <dirk@...ders.net>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     linux-kbuild@...r.kernel.org, Ulf Magnusson <ulfalizer@...il.com>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 00/12] kbuild/kconfig: do not update config during installation

Masahiro Yamada <yamada.masahiro@...ionext.com> writes:

> The main motivation of this patch series is to suppress the syncconfig
> during running installation targets.
>
> V1 consisted of only two patches:
>   https://patchwork.kernel.org/patch/10468105/
>   https://patchwork.kernel.org/patch/10468103/
>
> I noticed that installation targets would continue running
> even if the source tree is not configured at all
> because the inclusion of include/config/auto.conf was optional.
>
> So, I added one more patch in V2:
>  https://patchwork.kernel.org/patch/10483637/
>
> However, kbuild test robot reported a new warning message was displayed:
>
> Makefile:592: include/config/auto.conf: No such file or directory
>
> This warning is displayed only for Make 4.1 or older.
>
> To fix this annoying warning, I changed Kconfig too,
> which leaded to more clean-up, improvements in Kconfig.
>
> So, V3 is a big patch series.

Hello Masahiro,

I tested your series for a while, now.  I did not notice real issues
with it but want to leave some remarks about what I noticed in
the surroundings of your patches.

> Masahiro Yamada (12):
>   kconfig: rename file_write_dep and move it to confdata.c

I might be missing some trivial use-case, but when looking at this
patch, I noticed an inconsistency with the file names auto.conf and
auto.conf.cmd.

The first can be modified by an environment variable but when this
happens, auto.conf.cmd remains as is.  I noticed that only the
Documentation mentions that KCONFIG_AUTOCONFIG exists and confdata.c
uses it to serve the file name -- no other use anywhere.

Now, I am wondering if I just don't see an important case when the
use of KCONFIG_AUTOCONFIG is really helpful or even mandatory.

>   kconfig: split out helpers to check file/directory, create directory
>   kconfig: remove unneeded directory generation from local*config
>   kconfig: create directories needed for syncconfig by itself
>   kconfig: make syncconfig update .config regardless of sym_change_count

For this patch, I already mentioned that `conf --help' perhaps could be
updated.  On the other side, none of the entries there tells us such
details, so there is probably no need for syncconfig to do so.

>   kconfig: allow all config targets to write auto.conf if missing
>   kbuild: use 'include' directive to load auto.conf from top Makefile
>   kbuild: add .DELETE_ON_ERROR special target
>   kbuild: do not update config when running install targets
>   kbuild: do not update config for 'make kernelrelease'
>   kbuild: remove auto.conf and tristate.conf from prerequisites

In the surrounding of this patch I noticed -include of auto.conf and
tristate.conf in scripts/Makfile.modbuildin.  I tried it in some ways
but was not able to trigger that file being used with a missing
auto.conf.  On the other hand, if I now manually remove tristate.conf,
that would not be fixed or even noticed, because of -include and I
wonder if it is safer to also change the -includes in that file.

It seems, if one of those files is missing, one must have done it
manually or some other serious issue is present that we probably want to
notice.

Dirk

>   kbuild: replace include/config/%.conf with include/config/auto.conf
>
>  Makefile                    |  46 +++++++++------
>  scripts/Kbuild.include      |   3 +
>  scripts/kconfig/Makefile    |  16 ++---
>  scripts/kconfig/conf.c      |  39 +++++++------
>  scripts/kconfig/confdata.c  | 139 +++++++++++++++++++++++++++++++++++++-------
>  scripts/kconfig/gconf.c     |   1 +
>  scripts/kconfig/lkc.h       |   1 -
>  scripts/kconfig/lkc_proto.h |   2 +-
>  scripts/kconfig/mconf.c     |   1 +
>  scripts/kconfig/nconf.c     |   1 +
>  scripts/kconfig/qconf.cc    |   2 +
>  scripts/kconfig/util.c      |  30 ----------
>  12 files changed, 182 insertions(+), 99 deletions(-)