Re: [PATCHv3 6/8] x86/mm: Provide ARCH_GET_UNTAG_MASK and ARCH_ENABLE_TAGGED_ADDR

Peter Zijlstra
2022-06-16T09:40:14Z

On Fri, Jun 10, 2022 at 05:35:25PM +0300, Kirill A. Shutemov wrote:
> Add a couple of arch_prctl() handles:
>
> - ARCH_ENABLE_TAGGED_ADDR enabled LAM. The argument is required number
> of tag bits. It is rounded up to the nearest LAM mode that can
> provide it. For now only LAM_U57 is supported, with 6 tag bits.

As stated in the reply to the other patch; this isn't a 'for now' thing.
Due to how the untag thing works. Supporting U48 on 5-level kernels is
going to require a more complicated untag.