ARM Cortex-A50 系列应用处理器重点分析

The Cortex-A50 Series is the latest range of processors based on the ARMv8 architecture. The series includes support for the AArch64, a new energy efficient 64-bit execution state that operates alongside an enhanced version of ARM’s existing 32-bit execution state. The Cortex-A50 Series comprises the Cortex-A57 and the Cortex-A53 processors.

These new low power processors will drive the widespread adoption of technology applications ranging from gesture control, augmented reality, mobile gaming, web 2.0 and entrepreneurial business applications, where data is the business.

Both the Cortex-A57 and Cortex-A53 processors can operate independently or be combined into an ARM big.LITTLE processing configuration that enables scalable performance and optimal energy-efficiency.

为什么选择Cortex-A50处理器

Cortex-A50 series processors are excellent 32-bit processors with 64-bit capability. They deliver more performance for ARMv7 32-bit code in AArch32 execution state, and offer support for 64-bit data and larger virtual addressing space in AArch64 execution state.

The ARMv8 architecture allows clean interworking between 32-bit and 64-bit in AArch64 state, enabling a step-by step migration to 64-bit, beginning with 64-bit operating systems running 32-bit ARMv7 applications, migrating to a mix of 32-bit applications and 64-bit applications running in the same system.

With the ARMv8 architecture, the Cortex-A50 series processors also introduce more advanced SIMD capability, instructions to speed up software cryptography, increased register files, flexible addressing modes, support for tagged pointers, 64k data pages, a new exception model, enhanced cache management and enhanced floating point operations (IEEE754-2008).

Other features include load-acquire and store-release, which are an excellent match for the C++11, C11 and Java memory models, improving performance of thread-safe code by removing the need for explicit memory barrier instructions in many cases. Automatic event signaling enables power-efficient, high-performance spinlocks.

The Cortex-A53 and Cortex-A57 processors also introduce new power saving features such as retention modes and more extensive hierarchical clock gating to automatically save power when all or a portion of the processor is idle. While adding these new capabilities, the Cortex-A50 series processors are fully compatible with 32-bit ARMv7 software.

为什么选择64位

An obvious reason for 64-bit is the support of more than 4GB of physical memory; however this is achieved in ARMv7's LPAE extension on Cortex-A15 and Cortex-A7. Why then is 64-bit useful?

In server applications, OS and application software are frequently 64-bit today, so 64-bit pointers for virtual addressing are critical in these applications. Full support of AArch64, in addition to the power efficient ARMv8 architecture and power optimized microarchitectures, make Cortex-A50 series processors well suited to a broad range of applications in efficient low-power servers.

In the desktop environment, a larger virtual address space is important for modern desktop software APIs that may come to rely on having a vast virtual address space for techniques such as memory mapped file I/O and sparse addressing (e.g. for persistent objects). AArch64 also enables efficient 64-bit immediate generation meaning less need for literal pools.

A large program counter relative addressing range (+/-4GB) for efficient data addressing is helpful within shared libraries and position-independent executable. The ARMv8 instruction set, fully su