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

[Jan Beulich <jbeulich@xxxxxxxx>]

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