Re: [PATCH] core-parking: fix build with gcc12 and NR_CPUS=1

[Julien Grall <julien@xxxxxxx>]

Hi Jan,

On 09/09/2022 11:18, Jan Beulich wrote:
> Gcc12 takes issue with core_parking_remove()'s
>
>      for ( ; i < cur_idle_nums; ++i )
>          core_parking_cpunum[i] = core_parking_cpunum[i + 1];
>
> complaining that the right hand side array access is past the bounds of
> 1. Clearly the compiler can't know that cur_idle_nums can only ever be
> zero in this case (as the sole CPU cannot be parked).
>
> Beyond addressing the immediate issue also adjust core_parking_init():
> There's no point registering any policy when there's no CPU to park.
> Since this still doesn't result in the compiler spotting that
> core_parking_policy is never written (and hence is continuously NULL),
> also amend core_parking_helper() to avoid eventual similar issues there
> (minimizing generated code at the same time).
Given that CONFIG_NR_CPUS is a build time option. Wouldn't it be better
to set CONFIG_CORE_PARKING=n and provide dummy helper for any function 
that may be called unconditionally?
Cheers,

--
Julien Grall