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Cortex-A15 µarch
General Info
Arch Type	CPU
Designer	ARM Holdings
Manufacturer	TSMC
Introduction	September 8, 2010
Instructions
ISA	ARMv7
Succession
Cortex-A9 Cortex-A57

Cortex-A15 (codename Eagle) is the successor to the Cortex-A9, a low-power high-performance ARM microarchitecture designed by ARM Holdings for the mobile market. This microarchitecture is designed as a synthesizable IP core and is sold to other semiconductor companies to be implemented in their own chips. The A15 is the first microarchitecture specifically designed for high-performance, whereas the Cortex-A7, also the successor to the Cortex-A9, target high-efficiency.

The Cortex-A15 was often combined with a number of lower power cores (e.g. Cortex-A7) in a big.LITTLE configuration to achieve better energy/performance.

Compiler support

Compiler	Arch-Specific	Arch-Favorable
Arm Compiler	-mcpu=cortex-a15	-mtune=cortex-a15
GCC	-mcpu=cortex-a15	-mtune=cortex-a15
LLVM	-mcpu=cortex-a15	-mtune=cortex-a15

One can specify NEON support using the -mfpu=neon option. Note that GCC will not generate floating-point operations for auto-vectorization constructs because NEON, under ARMv7, is not fully IEEE 754-compliant. It's possible to use -funsafe-math-optimizations to circumvent that behavior.

If the Cortex-A15 is coupled with the Cortex-A7 in a big.LITTLE system, GCC also supports the following option:

Compiler	Tune
GCC	-mtune=cortex-a15.cortex-a7

Architecture

Key changes from Cortex-A9

• 28 nm process (from 40 nm)
• Longer pipeline (15+, up from 9-12)
  • 1.25x frequency (2.5 GHz, up from 2 GHz)
• 6x larger return stack size (48 entries, up from 8)
• Integer
  • Hardware division support
  • Hardware Fused Multiply-Accumulate
• VFPv4 (from VFPv3)
• NEONv2 (from NEON)
• Memory subsystem
  • Level 1 instruction cache switched to PIPT (from VIPT)
  • Level 1 instruction cache reduced to 2-way set associative (down from 4-way)
  • Level 1 data cache reduced to 2-way set associative (down from 4-way)
  • Added LPAE support

This list is incomplete; you can help by expanding it.

Block Diagram

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Memory Hierarchy

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Licensees

Arm named the following companies as licensees.

• Texas Instruments
• ST-Ericsson
• nVIDIA
• Samsung Electronics