[mixmastamyk]

Yes, this already happens. Address bus width is usually different from register width due to cost. I found this, old CPU's address bus only getting to 44 bits wide on Itanium.

https://www.tech-faq.com/address-bus.html

My newish AMD laptop: `grep 'address sizes' /proc/cpuinfo`

    address sizes : 48 bits physical, 48 bits virtual

Looks like 36 bits wide is already plenty for anything typical, up to 68 GB:

    >>> f'{2**32:>30_}'
    '                 4_294_967_296'
    >>> f'{2**36:>30_}'
    '                68_719_476_736'
    >>> f'{2**40:>30_}'
    '             1_099_511_627_776'
    >>> f'{2**48:>30_}'
    '           281_474_976_710_656'
    >>> f'{2**64:>30_}'
    '    18_446_744_073_709_551_616'

[ChocolateGod]

I guess no point wasting hardware supporting things that will never be possible for the lifetime of the processor.

[p_l]

AMD64 mandates 48bit virtual addressing minimum, with the rest sign-extended unless certain optional features are enabled.