FNSTENV

X87_ALU X87 x86_64

FNSTENV is an instruction of the x86_64 architecture (x86 / x86-64 (covers 16/32/64-bit modes)), category X87_ALU. This page lists its 2 encoding forms, distinguished by opcode byte: D9.

Each form below links to its full decode: the operand roles and where each one is encoded in the instruction, the flag and register effects, and any micro-op sequence authored for it.