ARMv8-A represents a fundamental change to the ARM architecture. It
adds an optional 64-bit architecture named "AArch64" and the
associated new "A64" instruction set. AArch64 provides user-space
compatibility with the existing 32-bit architecture ("AArch32" /
ARMv7-A) and instruction set ("A32"). The 16-32bit Thumb
instruction set is referred to as "T32" and has no 64-bit
counterpart. ARMv8-A allows 32-bit applications to be executed in a
64-bit OS and a 32-bit OS to be under the control of a 64-bit
hypervisor.[3] ARM announced their Cortex-A53 and Cortex-A57 cores
on 30 October 2012.[4] Apple was the first to release an ARMv8-A
compatible core (Cyclone) in a consumer product