A new core infrastructure improvement for the Linux kernel on ARM being worked on is enabling 128-bit page table entries (PTEs) with FEAT_D128 as a new optional feature of Armv9.3 and later.

FEAT_D128 allows selectively enabling VMSAv9-128 as a new translation system for handling 128 bit page table entries in order to support larger physical and virtual address memory ranges. Beyond the larger physical/virtual memory addressing, FEAT_D128 also enables more room for additional MMU management feature bits for both hardware and software.

The current Linux kernel patches for Arm's FEAT_D128 are under a request for comments (RFC) flag. There are also some known limitations such as KVM, Kernel Address Sanitizer, and other select features not currently being supported with FEAT_D128.

Those interested in this 128-bit page table entries support for ARM can see the RFC patch series for all the details.