ARMv8-A

Armv8-A

Announced in October 2011, Armv8-A (often called ARMv8 while the Armv8-R is also available) represents a fundamental change to the ARM architecture. It supports two Execution states: a 64-bit state named AArch64 and a 32-bit state named AArch32. In the AArch64 state, a new 64-bit A64 instruction set is supported; in the AArch32 state, two instruction sets are supported: the original 32-bit instruction set, named A32, and the 32-bit Thumb-2 instruction set, named T32. AArch32 provides user-space compatibility with Armv7-A. The processor state can change on an Exception level change; this allows 32-bit applications to be executed in AArch32 state under a 64-bit OS whose kernel executes in AArch64 state, and allows a 32-bit OS to run in AArch32 state under the control of a 64-bit hypervisor running in AArch64 state. ARM announced their Cortex-A53 and Cortex-A57 cores on 30 October 2012. Apple was the first to release an Armv8-A compatible core in a consumer product (Apple A7 in iPhone 5S). AppliedMicro, using an FPGA, was the first to demo Armv8-A. The first Armv8-A SoC from Samsung is the Exynos 5433 used in the Galaxy Note 4, which features two clusters of four Cortex-A57 and Cortex-A53 cores in a big.LITTLE configuration; but it will run only in AArch32 mode.