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. 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. 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.
