# RDPID — Read Processor ID

Opcode/Instruction | Op/En | 64/32-bit Mode | CPUID Feature Flag | Description
--- | --- | --- | --- | ---
F3 0F C7 /7 RDPID r32 | R | N.E./V | RDPID | Read IA32_TSC_AUX into r32.
F3 0F C7 /7 RDPID r64 | R | V/N.E. | RDPID | Read IA32_TSC_AUX into r64.

## Instruction Operand Encoding1 ¶

> 1.ModRM.MOD = 011B required

Op/En | Operand 1 | Operand 2 | Operand 3 | Operand 4
--- | --- | --- | --- | ---
R | ModRM:r/m (w) | N/A | N/A | N/A

## Description ¶

Reads the value of the IA32_TSC_AUX MSR (address C0000103H) into the destination register. The value of CS.D and operand-size prefixes (66H and REX.W) do not affect the behavior of the RDPID instruction.

## Operation ¶

    DEST := IA32_TSC_AUX

## Flags Affected ¶

None.

## Protected Mode Exceptions ¶

#UD | If the LOCK prefix is used.
If CPUID.7H.0:ECX.RDPID[bit 22] = 0.

## Real-Address Mode Exceptions ¶

Same exceptions as in protected mode.

## Virtual-8086 Mode Exceptions ¶

Same exceptions as in protected mode.

## Compatibility Mode Exceptions ¶

Same exceptions as in protected mode.

## 64-Bit Mode Exceptions ¶

Same exceptions as in protected mode.