rdpid

Read Processor ID

RDPID r32

Reads the processor ID (TSC_AUX) into register.

Pseudocode Operation

IF CPUID.RDPID = 0 THEN #UD FI;
dest[31:0] ← IA32_TSC_AUX[31:0];
dest[63:32] ← 0;

Example

RDPID eax

Encoding

Binary Layout
F3
+0
0F
+1
C7
+2
ModRM
+3
 
Format Legacy
Opcode F3 0F C7 /7
Extension RDPID

Operands

  • dest
    32-bit general-purpose register (e.g. EAX)

Related

More in RDPID

Reference

View in Intel® 64 and IA-32 Architectures SDM ↗ Intel® SDM

Instruction Forms

Opcode Instruction Op/En 64/32-bit Mode CPUID Description
F3 0F C7 /7 RDPID R N.E./V Read IA32_TSC_AUX into r32. RDPID r32
F3 0F C7 /7 RDPID R V/N.E. R Read IA32_TSC_AUX into r64. RDPID r64 Instruction Operand Encoding1 Op/En Operand 1 Operand 2 Operand 3 Operand 4 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.

Exceptions

Protected Mode Exceptions

#UD If the LOCK prefix is used. If CPUID.07H.00H:ECX.RDPID[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. 1.ModRM.MOD = 011B required RDPID-Read Processor ID Vol. 2B 4-548