> * "32-bit" NetBSD kernels should probably just punt and use 32-bit
>   entrylo regs, and
> 
> * "64-bit" kernels should use 64-bit PTEs.
> 
> However, until the latter actually exist, it might be annoying to
> remove the ability to use 64-bit entrylo regs from the (32-bit)
> kernel.

64bit PTE is necessary for specific combinations of 40bit PFN capable
processor _and_ 40bit physical address computer hardware design.
It's not coupled with 64bit kernel itself.

Back to mipsX_subr.S, the _MTC0/_MFC0 is not designed for
40bit case after all.

Toru Nishimura/ALKYL Technology