Re: [RFCv2 08/10] x86/mm: Make LAM_U48 and mappings above 47-bits mutually exclusive

Thomas Gleixner
2022-05-12T13:36:40Z

On Wed, May 11 2022 at 05:27, Kirill A. Shutemov wrote:
> LAM_U48 steals bits above 47-bit for tags and makes it impossible for
> userspace to use full address space on 5-level paging machine.

> Make these features mutually exclusive: whichever gets enabled first
> blocks the othe one.

So this patch prevents a mapping above 47bit when LAM48 is enabled, but
I fail to spot how an already existing mapping above 47bit would prevent
LAM48 from being enabled.

Maybe I'm missing something which makes this magically mutually
exclusive.

Thanks,

tglx