On Mon, Jul 18, 2022 at 07:39:22PM +0200, Alexander Potapenko wrote: > On Wed, Jul 13, 2022 at 1:13 AM Kirill A. Shutemov > <kirill.shutemov@xxxxxxxxxxxxxxx> wrote: > > > > 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. > > > > LAM_U48 enabling is controversial since it competes for bits with > > 5-level paging. Its enabling isolated into an optional last patch that > > can be applied at maintainer's discretion. > > I believe having optional patches will put unnecessary burden on > distro maintainers. > Soon after landing U48 support other changes will start piling on top > of it, and it will be impossible to maintain a kernel with this patch > removed. > It also won't make any difference for the upstream, where this patch > will be always present. > > We'd better decide now whether we need U48 or not, and either keep it > or delete it. Dave, Andy, any position on this? I wrote LAM_U48 support to prove that interface is flexible enough, but I see why it can be a problem if a distro will pick them up ahead of upstream. -- Kirill A. Shutemov
