> Thumb-2, [...] are mandatory instruction extension sets for ARM64 Isn't Thumb-2 for 32-bit ARM only? AFAIK, having 32-bit ARM is optional, you can have 64-bi

> Thumb-2, [...] are mandatory instruction extension sets for ARM64 Isn't Thumb-2 for 32-bit ARM only? AFAIK, having 32-bit ARM is optional, you can have 64-bit only ARM nowadays. (And 64-bit ARM no longer has what is IMO the least RISC instructions from 32-bit ARM: the "load multiple" and "store multiple" instructions, which had a built-in loop doing memory accesses to an arbitrary set of registers, were replaced by "load pair" and "store pair", which do a single memory access and work with a fixed number of registers. If you look at https://www.righto.com/2016/01/more-arm1-processor-reverse-engineering.html https://www.righto.com/2016/01/more-arm1-processor-reverse-e... you can see that the circuitry dedicated for these instructions took a lot of space in the original 32-bit ARM core.)