lkml.org 
[lkml]   [2022]   [May]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [RFCv2 00/10] Linear Address Masking enabling
    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?

    \
     
     \ /
      Last update: 2022-05-11 08:51    [W:2.519 / U:0.356 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site