Re: [PATCH v2 1/3] x86/retpoline: rename retpoline Kconfig check to include GCC prefix

[Jan Beulich <jbeulich@xxxxxxxx>]

On 16.02.2022 17:21, Roger Pau Monne wrote:
> Current retpoline checks apply to GCC only, so make it obvious by
> prefixing the Kconfig option with GCC. Keep the previous option as a
> way to signal generic retpoline support regardless of the underlying
> compiler.
> 
> No functional change intended.
> 
> Signed-off-by: Roger Pau Monné <roger.pau@xxxxxxxxxx>
> Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
> ---
> Changes since v1:
>  - Put def_bool before depend on.

Just for the record: A slightly shorter alternative would have been ...

> --- a/xen/arch/x86/Kconfig
> +++ b/xen/arch/x86/Kconfig
> @@ -32,9 +32,13 @@ config ARCH_DEFCONFIG
>       string
>       default "arch/x86/configs/x86_64_defconfig"
>  
> -config INDIRECT_THUNK
> +config GCC_INDIRECT_THUNK
>       def_bool $(cc-option,-mindirect-branch-register)
>  
> +config INDIRECT_THUNK
> +     def_bool y
> +     depends on GCC_INDIRECT_THUNK

config INDIRECT_THUNK
        bool

config GCC_INDIRECT_THUNK
        def_bool $(cc-option,-mindirect-branch-register)
        select INDIRECT_THUNK

A more appropriate thing to use for "depends on" might have been
CC_IS_GCC. With the next patch in mind this would then avoid
potential confusion if e.g. Clang folks decided to (also) support
the gcc style command line options.

Jan