30.6.2.1. ARMv8 floating point availability
Support is semi-mandatory. ARMv8 architecture reference manual A1.5 "Advanced SIMD and floating-point support":
ARMv8 can support the following levels of support for Advanced SIMD and floating-point instructions:
Full SIMD and floating-point support without exception trapping.
Full SIMD and floating-point support with exception trapping.
No floating-point or SIMD support. This option is licensed only for implementations targeting specialized markets.
Note: All systems that support standard operating systems with rich application environments provide hardware support for Advanced SIMD and floating-point. It is a requirement of the ARM Procedure Call Standard for AArch64, see Procedure Call Standard for the ARM 64-bit Architecture.
Therefore it is in theory optional, but highly available.
This is unlike ARMv7, where floating point is completely optional through ARM VFP.