[Joker_vD]

Yeah, but I'm talking about lower bits, not the upper bits.

Off-tangent: virtual pointers on AMD64 are effectively signed numbers and yet most low-level intro-level programming books keep saying that "pointers are unsigned ints because it doesn't make sense for pointers to be negative, bla-bla". Hell, I believe xv6 book has this passage and the passage about pointers' upper-bits on AMD64 being either all 1 or 0 on the same page!

[gpderetta]

Ah, ok, but now you can't do subword aligned read/writes. That was a costly mistake that Alpha originally made and most architectures have avoided since.

[Joker_vD]

That depends on ISA's details, honestly. For example, Knuth's MMIX has 64-bit words and has separate intructions to load/store 8-, 16-, 32-, or 64-bit wide chunks of data to/from memory — which are forced to be naturally aligned because 0, 1, 2, or 3 lower bits of the address are masked, depending on the data access's width. So there you go, you have aligned access for all "natural" subword sizes.