Eh? The values you can store in the tags are absolutely dependent on the number of available bits. That’s a simple type safety problem. This requirement is arch

Eh? The values you can store in the tags are absolutely dependent on the number of available bits. That’s a simple type safety problem. This requirement is architecture independent. You can’t cram 8 bits of tag in 7 bits if the latter is all the architecture has available. Hence why you have to design for the smallest reliable target.