Re: [PATCH v4] memregion: Add cpu_cache_invalidate_memregion() interface

[Davidlohr Bueso]

On Thu, 27 Oct 2022, Dave Hansen wrote:

> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 67745ceab0db..b68661d0633b 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -69,6 +69,7 @@ config X86
> > 	select ARCH_ENABLE_THP_MIGRATION if X86_64 && TRANSPARENT_HUGEPAGE
> > 	select ARCH_HAS_ACPI_TABLE_UPGRADE	if ACPI
> > 	select ARCH_HAS_CACHE_LINE_SIZE
> > +	select ARCH_HAS_CPU_CACHE_INVALIDATE_MEMREGION  if X86_64
>
> What is 64-bit only about this?
>
> I don't expect to have a lot of NVDIMMs or CXL devices on 32-bit
> kernels, but it would be nice to remove this if it's not strictly
> needed.  Or, to add a changelog nugget that says:
>
> 	Restrict this to X86_64 kernels.  It would probably work on 32-
> 	bit, but there is no practical reason to use 32-bit kernels and
> 	no one is testing them.

Yes, this was to further limit the potential users.