Re: [PATCH 02/12] x86: Add more granularity to the vendors in Kconfig

[Alejandro Vallejo <alejandro.garciavallejo@xxxxxxx>]

On Wed Feb 11, 2026 at 5:06 PM CET, Jan Beulich wrote:
> On 06.02.2026 17:15, Alejandro Vallejo wrote:
>> --- a/xen/arch/x86/Kconfig.cpu
>> +++ b/xen/arch/x86/Kconfig.cpu
>> @@ -19,4 +19,47 @@ config INTEL
>>        May be turned off in builds targetting other vendors.  Otherwise,
>>        must be enabled for Xen to work suitably on Intel platforms.
>>  
>> +config HYGON
>> +    bool "Support Hygon CPUs"
>> +    select AMD
>> +    default y
>> +    help
>> +      Detection, tunings and quirks for Hygon platforms.
>> +
>> +      May be turned off in builds targetting other vendors.  Otherwise,
>> +      must be enabled for Xen to work suitably on Hygon platforms.
>> +
>> +
>> +config CENTAUR
>> +    bool "Support Centaur CPUs"
>> +    select INTEL
>> +    default y
>> +    help
>> +      Detection, tunings and quirks for Centaur platforms.
>> +
>> +      May be turned off in builds targetting other vendors.  Otherwise,
>> +      must be enabled for Xen to work suitably on Centaur platforms.
>> +
>> +config SHANGHAI
>> +    bool "Support Shanghai CPUs"
>> +    select INTEL
>> +    default y
>> +    help
>> +      Detection, tunings and quirks for Shanghai platforms.
>> +
>> +      May be turned off in builds targetting other vendors.  Otherwise,
>> +      must be enabled for Xen to work suitably on Shanghai platforms.
>> +
>> +config UNKNOWN_CPU_VENDOR
>> +    bool "Support unknown CPU vendors"
>> +    default y
>> +    help
>> +      This option prevents a panic on boot when the host CPU vendor isn't
>> +      supported by going into a legacy compatibility mode and not applying
>> +      any relevant tunings or quirks.
>> +
>> +      Not selecting this options while selecting multiple vendors doesn't 
>> have
>> +      any major effect on code size, but selecting a single vendor with this
>> +      option cleared produces a much smaller build.
>
> Shouldn't this option's prompt be suppressed when all other vendors were
> selected off? Else the degenerate case can result that I mentioned in
> reply to patch 03.
>
> Jan

You mean having the option disappear when any explicit vendor is enabled?

I guess we could. It wouldn't be very obvious to the user this can be toggled,
but now again, if they are unticking vendors they would end up noticing.

Cheers,
Alejandro