42 bits?

[Simone Bordet]

Hi,

while researching about ZGC, I could not find an authoritative source
that says that Intel CPUs are limited to 42 bits for addressing
memory, and therefore ZGC uses bits 0-41 for addressing, 42-45 for
metadata.

OTOH, I found that there is a somewhat agreement in the search results
I found (e.g. https://en.wikipedia.org/wiki/X86-64) that 48 bits are
used for addressing memory.

Just curious. Thanks for shedding some light on this.

-- 
Simone Bordet
---
Finally, no matter how good the architecture and design are,
to deliver bug-free software with optimal performance and reliability,
the implementation technique must be flawless.   Victoria Livschitz