On Wed, May 11, 2022 at 05:27:40AM +0300, Kirill A. Shutemov wrote: > Hi all. Here's long overdue update on LAM enabling. > > # Description # > > Linear Address Masking[1] (LAM) modifies the checking that is applied to > 64-bit linear addresses, allowing software to use of the untranslated > address bits for metadata. > > The patchset brings support for LAM for userspace addresses. > > The most sensitive part of enabling is change in tlb.c, where CR3 flags > get set. Please take a look that what I'm doing makes sense. > > The feature competes for bits with 5-level paging: LAM_U48 makes it > impossible to map anything about 47-bits. The patchset made these > capability mutually exclusive: whatever used first wins. LAM_U57 can be > combined with mappings above 47-bits. So aren't we creating a problem with LAM_U48 where programs relying on it are of limited sustainability? Any such program simply *cannot* run on 5 level pagetables. Why do we want to do this?
