Intel CPU instruction mnemonic. The linux kernel for x86 includes support for the cpuid instruction. The following code is used as of 2.5.59: /* * Generic CPUID function */ static inline void cpuid(int op, int *eax, int *ebx, int *ecx, int *edx) { __asm__("cpuid" : "=a" (*eax), "=b" (*ebx), "=c" (*ecx), "=d" (*edx) : "0" (op)); } Other architectures implement cpuid functions as well. This inline assembly specifies that output from this instruction will go to the EAX, EBX, ECX, and EDX registers. In input operand is constrained to being the same as the 0th output operand, in other words EAX. The cpuid instruction has three input operand values, each which return a different set of information about the target processor. Refer to the Intel instruction set reference for more information. There is a program by Phil Karn (KA9Q) called cpuid which calls this instruction as well. /include/asm-i386/processor.h Intel instruction set manual Entry created: Wed Mar 19 21:26:37 EST 2003 Entry owner: Michael Still (mikal@stillhq.com) Status: Unfinalized