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发帖数: 20761 | 1 ARMv8 and 64-bit[edit source | editbeta]
Released in late 2011, ARMv8 represents a fundamental change to the ARM
architecture. It adds a 64-bit architecture, named "AArch64", and a new "A64
" instruction set. Within the context of ARMv8, the 32-bit architecture and
instruction set are referred to as "AArch32" and "A32" respectively. The
Thumb instruction sets are referred to as "T32" and have no 64-bit
counterpart. ARMv8 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.[1] Applied
Micro, AMD, Broadcom, Calxeda, HiSilicon, Samsung, ST Microelectronics and
other companies have announced implementation plans.[51][52][53][54] ARM
announced their Cortex-A53 and Cortex-A57 cores on 30 October 2012.[23]
Apple announced on September 10, 2013 that the iPhone 5s will use the 64-bit
ARMv8 Apple A7 SOC.
To both AArch32 and AArch64, ARMv8 makes VFPv3/v4 and advanced SIMD (NEON)
standard. It also adds cryptography instructions supporting AES and SHA-1/
SHA-256.
AArch64 features:
New instruction set, A64
Has 31 general-purpose 64-bit registers.
Separate dedicated SP and PC.
Instructions are still 32 bits long and mostly the same as A32 (with LDM/STM
instructions and most conditional execution dropped).
Most instructions can take 32-bit or 64-bit arguments.
Addresses assumed to be 64-bit.
Advanced SIMD (NEON) enhanced
Has 32 × 128-bit registers (up from 16), also accessible via VFPv4.
Supports double-precision floating point.
Fully IEEE 754 compliant.
AES encrypt/decrypt and SHA-1/SHA-2 hashing instructions also use these
registers.
A new exception system
Fewer banked registers and modes.
Memory translation from 48-bit virtual addresses based on the existing LPAE,
which was designed to be easily extended to 64-bit
OS support:
Linux – patches adding ARMv8 support have been posted for review by Catalin
Marinas of ARM Ltd. The patches have been included in Linux kernel version
3.7 in late 2012.[55]
iOS - iOS 7 on the 64-bit Apple A7 SOC has ARMv8 application support. |
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