x86-64.net

Instruction

RDPID

Reads the processor ID that the kernel stored in IA32_TSC_AUX (on Linux, the CPU and node number) without reading the time-stamp counter.

Extensions
Forms
2 (2 Legacy)
Data
Intel XED v2026.08.23

Forms

Every encoding of RDPID that Intel XED knows, one row per XED instruction form (iform). How to read the notation.
InstructionEncodingRequires
RDPID r32 not in 64-bit mode RDPID_GPR32u32F3 0F C7 /7RDPID
RDPID r64 64-bit mode only RDPID_GPR64u64F3 0F C7 /7RDPID

Intrinsics

The C intrinsics of Clang 23.1.2 that compile to RDPID, each with the form it compiles to and the Clang options it needs. The forms come from compiling every intrinsic and decoding the result with Intel XED; all intrinsics A–Z explains the method.

IntrinsicCompiles to
_rdpid_u32 unsigned int _rdpid_u32(void)

RDPID r64 Legacy -mrdpid

CPUID and processors

Each form belongs to an XED ISA set. A form can be used when the processor reports every CPUID bit of one of its ISA set's alternatives.

CPUID requirements and processors of the XED ISA sets above. Alternatives are separated by “or”; processors follow XED’s chip model, which covers AMD processors up to Zen 2.
ISA setCPUIDProcessors in XED
RDPID

RDPID
CPUID.(EAX=07H,ECX=0):ECX[22] RDPID

Ice Lake (client), Tiger Lake, Alder Lake, Arrow Lake, Panther Lake, Nova Lake, Ice Lake (server), Sapphire Rapids, Emerald Rapids, Granite Rapids, Diamond Rapids, Goldmont Plus, Tremont, Snow Ridge, Lakefield, Sierra Forest, Clearwater Forest, Zen 2

Sources

  1. Intel XED v2026.08.23 (commit 0bcb6237345c): forms, encodings, ISA sets, CPUID bits and chip model.
  2. Clang's x86 intrinsic headers, LLVM 23.1.2 (commit 85ac56026243): the intrinsics, their signatures and doc comments, and the Clang of that release, which compiled each of them.
  3. Intel 64 and IA-32 Architectures Software Developer's Manual, Volume 2 (325383-092, June 2026)
  4. Linux arch/x86/include/asm/segment.h: the CPU and node number in IA32_TSC_AUX

The tables are derived from Intel XED, Copyright Intel Corporation, licensed under the Apache License 2.0; x86-64.net converted and reformatted them. The intrinsics and their signatures come from Clang, part of the LLVM Project, licensed under the Apache License 2.0 with LLVM Exceptions. The text is our own.