This content has not been validated; it was AI-generated following the x86-64 ISA Documentation generation process to maintain high quality. However, as no human has verified this data, errors may exist. If the accuracy of this data is critical, please consult the Intel SDM. The model used to generate this is gemma4:31b

WRSSD

Writes a 64-bit value from a register to a specified location in the Single Precision Floating-Point Control and Status Register (MXCSR) based on an index provided in a register.

The following table covers what the source and destinations can be.

DO NOT support LOCK

This instruction is only available in 64-bit mode. It is NOT supported in compatibility mode.

The destination operand MUST be a memory location; however, it acts as a pointer to the MXCSR register via an index. The index provided in the source register MUST be within the valid range for the MXCSR register; otherwise, the behavior is undefined.

The instruction uses a specific addressing mechanism to target the MXCSR register. Ensure that the memory operand refers to a valid memory-mapped or architectural interface for the control register to avoid general protection faults.