On Thu, Aug 29, 2024 at 09:54:08AM -0700, Dave Hansen wrote: > On 8/28/24 13:15, Charlie Jenkins wrote: > > A way to restrict mmap() to return LAM compliant addresses in an entire > > address space also doesn't have to be mutually exclusive with this flag. > > This flag allows for the greatest degree of control from applications. > > I don't believe there is additionally performance saving that could be > > achieved by having this be on a per address space basis. > > I agree with you in general. The MAP_BELOW_HINT _is_ the most flexible. > But it's also rather complicated. Can you expand upon what you mean by it being complicated? Complicated for the kernel or complicated for a user? > > My _hope_ would be that a per-address-space property could share at > least some infrastructure with what x86/LAM and arm/TBI do to the > address space. Basically put the restrictions in place for purely > software reasons instead of the mostly hardware reasons for LAM/TBI. That is a good point, perhaps that would be a way to hook this into LAM, TBI, and any other architecture's specific address masking feature. - Charlie > > Lorenzo also raised some very valid points about a having a generic > address-restriction ABI. I'm certainly not discounting those concerns. > It's not something that can be done lightly.
