Linux 5.18 To Bring RISC-V sv57 Support For 5-Level Page Tables
Queued up in the Linux RISC-V's "for-next" branch over the past week is support for the sv57 extension this royalty-free processor ISA. RISC-V sv57 allows for 57-bit page-based virtual memory system support for cases where the sv48 support is insufficient. The sv57 extension adds the fifth level of the page table.
The sv57 extension underwent its public review in late 2021. The sv57 support is now in riscv's for-next branch ahead of the Linux 5.18 merge window opening next month. The sv57 support is enabled by default and will fall-back to sv48 / 4 level page tables in cases where the platform does not support sv57. In turn Linux then also falls back to 3 level page tables when sv48 is not supported.