[RESEND v3 2/2] drm: Add CONFIG_DRM_WERROR

[Jani Nikula]

On Wed, 27 Mar 2024, Nathan Chancellor <nathan at kernel.org> wrote:
> On Wed, Mar 27, 2024 at 09:59:01AM +0200, Jani Nikula wrote:
>> An alternative would be to "depends on !COMPILE_TEST" that we have in
>> i915, but then some folks want to have COMPILE_TEST in drm, because some
>> drivers are otherwise hard for people to build.
>
> Right. I think it is unfortunate how (at least in my opinion)
> CONFIG_COMPILE_TEST has two meanings: genuinely just compile testing or
> "allmodconfig". For the first case, we would want CONFIG_DRM_WERROR=y
> but for the second case, it would be nice for CONFIG_DRM_WERROR to
> default to off (because CONFIG_WERROR is enabled) but allow developers
> to turn it on explicitly.

Yes, CONFIG_COMPILE_TEST has become overloaded.

> Another lofty/wistful idea to solve this would be to implement something
> similar to compiler diagnostic groups for Kconfig, where there would be
> a hierarchy like
>
>   CONFIG_WERROR
>     CONFIG_DRM_WERROR
>     CONFIG_SUBSYSTEM_A_WERROR
>     CONFIG_SUBSYSTEM_B_WERROR
>
> where the value of CONFIG_WERROR is the same value for all
> subconfigurations under it but they could still be enabled individually
> without any additional dependencies (ala something like '-Wno-unused
> -Wunused-variable'), which would allow my use case of CONFIG_WERROR=n
> removing all instances of -Werror to continue to work but allow other
> developers and CI systems to just set their specific -Werror
> configuration and be done with it. I don't think something like that
> exists but maybe I don't know Kconfig as well as I think I do :)

Yet another idea is to have a way to mark a config option "manual", that
is, never enable this automatically under any circumstances, not in make
allyesconfig or allmodconfig, don't ask in make oldconfig, don't allow
selects. The only way to enable is to toggle it manually. If you want it
and enable it and see problems, it's on you.

CONFIG_WERROR and CONFIG_DRM_WERROR could both be like this. The problem
with them is that they're not so much different configurations, they are
about how to deal with build errors, and that's not really what, say,
make allyesconfig should be about.

BR,
Jani.


-- 
Jani Nikula, Intel