[rdmsr]

Fun fact: physical addresses will still have at most 52 bits, despite linear address space having up to 57.

[ChuckMcM]

And that is a huge improvement from the old 40 bit limit, and then the 42 bit limit. In fact it is over 1000x better than the 52 bit limit :-)

[Symmetry]

For garbage collectors and other things you really want a randomly selected number to only infrequently be a valid address.

[tedunangst]

How often do garbage collectors look at physical addresses?

[Symmetry]

... You're right, physical address bits are totally irrelevant and I was confused.

[bogomipz]

I'm guessing this is tradeoff of practical vs possible?