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

[Jan Beulich <jbeulich@xxxxxxxx>]

On 17.02.2022 09:59, Jan Beulich wrote:
> 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

Oh, looking at patch 3 again (which I should have still had in mind)
this would of course not help. Yet ..

> 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.

... adding this dependency (and a respective one in patch 2) might
still be a good thing.

Jan