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author | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-06-17 10:51:52 +0000 |
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committer | Daniel Baumann <daniel.baumann@progress-linux.org> | 2024-06-17 10:51:52 +0000 |
commit | 4ad94864781f48b1a4b77f9cfb934622bf756ba1 (patch) | |
tree | 3900955c1886e6d2570fea7125ee1f01bafe876d /upstream/opensuse-tumbleweed/man4/cpuid.4 | |
parent | Adding upstream version 4.22.0. (diff) | |
download | manpages-l10n-4ad94864781f48b1a4b77f9cfb934622bf756ba1.tar.xz manpages-l10n-4ad94864781f48b1a4b77f9cfb934622bf756ba1.zip |
Adding upstream version 4.23.0.upstream/4.23.0
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'upstream/opensuse-tumbleweed/man4/cpuid.4')
-rw-r--r-- | upstream/opensuse-tumbleweed/man4/cpuid.4 | 28 |
1 files changed, 15 insertions, 13 deletions
diff --git a/upstream/opensuse-tumbleweed/man4/cpuid.4 b/upstream/opensuse-tumbleweed/man4/cpuid.4 index 3f7d184f..a09d87a5 100644 --- a/upstream/opensuse-tumbleweed/man4/cpuid.4 +++ b/upstream/opensuse-tumbleweed/man4/cpuid.4 @@ -3,19 +3,19 @@ .\" .\" SPDX-License-Identifier: Linux-man-pages-copyleft .\" -.TH cpuid 4 2022-10-30 "Linux man-pages 6.05.01" +.TH cpuid 4 2024-05-02 "Linux man-pages (unreleased)" .SH NAME cpuid \- x86 CPUID access device .SH DESCRIPTION CPUID provides an interface for querying information about the x86 CPU. -.PP +.P This device is accessed by .BR lseek (2) or .BR pread (2) to the appropriate CPUID level and reading in chunks of 16 bytes. A larger read size means multiple reads of consecutive levels. -.PP +.P The lower 32 bits of the file position is used as the incoming .IR %eax , and the upper 32 bits of the file position as the incoming @@ -24,7 +24,7 @@ the latter is intended for "counting" .I eax levels like .IR eax=4 . -.PP +.P This driver uses .IR /dev/cpu/CPUNUM/cpuid , where @@ -34,7 +34,7 @@ and on an SMP box will direct the access to CPU .I CPUNUM as listed in .IR /proc/cpuinfo . -.PP +.P This file is protected so that it can be read only by the user .IR root , or members of the group @@ -44,7 +44,7 @@ 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. -.PP +.P Most of the information in .I cpuid is reported by the kernel in cooked form either in @@ -53,29 +53,31 @@ or through subdirectories in .IR /sys/devices/system/cpu . Direct CPUID access through this device should only be used in exceptional cases. -.PP +.P The .I cpuid driver is not auto-loaded. On modular kernels you might need to use the following command to load it explicitly before use: -.PP +.P .in +4n .EX $ modprobe cpuid .EE .in -.PP +.P There is no support for CPUID functions that require additional input registers. -.PP -Very old x86 CPUs don't support CPUID. +.P +Early i486 CPUs do not support the CPUID instruction; +.\" arch/x86/kernel/cpuid.c cpuid_open() +opening this device for those CPUs fails with EIO. .SH SEE ALSO .BR cpuid (1) -.PP +.P Intel Corporation, Intel 64 and IA-32 Architectures Software Developer's Manual Volume 2A: Instruction Set Reference, A-M, 3-180 CPUID reference. -.PP +.P Intel Corporation, Intel Processor Identification and the CPUID Instruction, Application note 485. |