this post was submitted on 23 Jun 2024
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276
Why we don't have 128-bit CPUs (www.xda-developers.com)
submitted 5 months ago by [email protected] to c/[email protected]
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[–] [email protected] 36 points 5 months ago (1 children)

I actually added detail that wasn't already discussed in the article?

[–] [email protected] 33 points 5 months ago (1 children)

I actually didn’t know that about addressing before your comment and so I found it very interesting, thanks

[–] [email protected] 2 points 5 months ago

Some applications use those unused bits to add tags to pointers but it's important to mask those out before attempting to dereference the address. I'm not sure about ARM but x86-64 requires bits 49-63 to be copies of bit 48 (kinda like sign-extension), ironically to ensure that no one is using those bits to store extra data.