Re: [PATCH 2/2] x86/pat: add functions to query specific cache mode availability

[Christoph Hellwig]

On Tue, May 03, 2022 at 03:22:07PM +0200, Juergen Gross wrote:
> Some drivers are using pat_enabled() in order to test availability of
> special caching modes (WC and UC-). This will lead to false negatives
> in case the system was booted e.g. with the "nopat" variant and the
> BIOS did setup the PAT MSR supporting the queried mode, or if the
> system is running as a Xen PV guest.
> 
> Add test functions for those caching modes instead and use them at the
> appropriate places.
> 
> For symmetry reasons export the already existing x86_has_pat_wp() for
> modules, too.

No, we never export unused functionality.