We don’t even have true 64-bit addressing yet. x86-64 uses only 48 bits of a 64 bit address and 64-bit ARM can use anything between 40 and 52 depending on the specific configuration.
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.
We don’t even have true 64-bit addressing yet. x86-64 uses only 48 bits of a 64 bit address and 64-bit ARM can use anything between 40 and 52 depending on the specific configuration.
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I think they were just adding to the conversation
I actually added detail that wasn’t already discussed in the article?
I actually didn’t know that about addressing before your comment and so I found it very interesting, thanks
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.
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that was a nice chuckle.ty