Simple manpage for the cpuid devices. -Andi .\" Description based on comment in arch/x86/kernel/cpuid.c .TH MSR 7 2009-02-22 "Linux" "Linux Programmer's Manual" .SH NAME cpuid \- x86 CPUID access device .SH DESCRIPTIONS CPUID allows to query information about the x86 CPU. This device is accessed by .I lseek(2) or .I pread(2) to the appropriate CPUID level and then read in chunks of 16 bytes. A larger size means multiple reads of consecutive levels. The lower 32 bits of the file position is used as the incoming %eax, and the upper 32 bits of the file position as the incoming %ecx, the latter intended for "counting" eax levels like eax=4. This driver uses .I /dev/cpu/CPUNUM/cpuid where .I CPUNUM is the minor number, and on an SMP box will direct the access to CPU CPUNUM as listed in .I /proc/cpuinfo. .SH NOTES The CPUID instruction can be directly executed by a program using inline assembler. However this device allows convenient access to all CPUs without changing process affinity. Most of the information in CPUID is reported by the kernel in cooked form either in .I /proc/cpuinfo or through sub directories in .I /sys/devices/system/cpu Direct cpuid access through this device should only be used in exceptional cases. The .I cpuid driver is not auto-loaded. On modular kernel you might need to use .B modprobe cpuid to load it explicitely before use. There is no support for cpuid functions that require additional input registers. Very old x86 CPUs don't support CPUID. .SH SEE ALSO Intel Corporation, Intel 64 and IA-32 Architectures Software Developer's Manual Volume 2A Instruction Set Reference, A-M, 3-180 CPUID reference. Intel Corporation, Intel Processor Identification and the CPUID Instruction, Application note 485. -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
