linux-kernel - Re: [PATCH] kbuild: fix W= option checks for extra DTC warnings

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Date:   Thu, 18 Jan 2018 10:25:54 +0100
From:   Arnd Bergmann <arnd@...db.de>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        DTML <devicetree@...r.kernel.org>, Rob Herring <robh@...nel.org>,
        Sam Ravnborg <sam@...nborg.org>,
        Michal Marek <michal.lkml@...kovi.net>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kbuild: fix W= option checks for extra DTC warnings

On Thu, Jan 18, 2018 at 4:31 AM, Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
> Kbuild supports 3 levels of extra warnings, and multiple levels can
> be combined, like W=12, W=123.  It was added by commit a6de553da01c
> ("kbuild: Allow to combine multiple W= levels").
>
> From the log of commit 8654cb8d0371 ("dtc: update warning settings
> for new bus and node/property name checks"), I assume:
>
>  - unit_address_vs_reg, simple_bus_reg, etc. belong to level 1
>  - node_name_chars_strict, property_name_chars_strict belong to level 2
>
> However, the level 1 warnings are displayed by any argument to W=.
> On the other hand, the level 2 warnings are displayed by W=2, but
> not by W=12, or W=123.
>
> Use $(findstring ...) like scripts/Makefile.extrawarn.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>

Good catch!

Acked-by: Arnd Bergmann <arnd@...db.de>

> Side Notes for possible additional works:
>
>  [1] I implemented DTC extra warnings differently in U-Boot:
>
>     https://github.com/u-boot/u-boot/blob/v2018.01/scripts/Makefile.extrawarn#L64
>
>     Better to collect extra warning stuff into scripts/Makefile.extrawarn ?
>
>  [2] KBUILD_ENABLE_EXTRA_GCC_CHECKS is getting a historical misnomer
>      because we use it for Clang and DTC too.
>
>      Better to rename?  (keeping backward-compatibility for a while)?

I'd suggest we leave it for now, I still plan to eventually do my
large rework of
the way we handle extra warning levels, likely that will result in
Makefile.extrawarn
being completely replaced.

       Arnd