Architecture support for NEON
NEON technology is an optional extension to the ARM architecture. There are versions that provide additional instructions.
The NEON extension is optionally available only for the ARMv7-A and ARMv7-R architectures. All NEON instructions, with the exception of half-precision and fused multiply-add instructions, are available on systems that support NEON. Some of these instructions are also available on systems that implement the VFP extension without NEON. These are called shared instructions.
NEON instructions, including the half-precision and fused multiply-add instructions, are treated as Undefined Instructions on systems that do not support the necessary architecture extension. Even on systems that support NEON, the instructions are undefined if the necessary coprocessors are not enabled in the Coprocessor Access Control Register (CP15 CPACR).