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End users frequently want to know what features their processor
supports, independent of what the kernel supports.
/proc/cpuinfo is great. It is omnipresent and since it is provided by
the kernel it is always as up to date as the kernel. But, it could be
ambiguous about processor features which can be disabled by the kernel
at boot-time or compile-time.
There are some user space tools showing more raw features, but they are
not bound with kernel, and go with distros. Many end users are still
using old distros with new kernels (upgraded by themselves), and may
not upgrade the distros only to get a newer tool.
So here arise the need for a new tool, which
* shows raw CPU features read from the CPUID instruction
* will be easier to update compared to existing userspace
tooling (perhaps distributed like perf)
* inherits "modern" kernel development process, in contrast to some
of the existing userspace CPUID tools which are still being developed
without git and distributed in tarballs from non-https sites.
* Can produce output consistent with /proc/cpuinfo to make comparison
easier.
The CPUID leaf definitions are kept in an .csv file which allows for
updating only that file to add support for new feature leafs.
This is based on prototype code from Borislav Petkov
(http://sr71.net/~dave/intel/stupid-cpuid.c).
[ bp:
- Massage, add #define _GNU_SOURCE to fix implicit declaration of
function ‘strcasestr' warning
- remove superfluous newlines
- fallback to cpuid.csv in the current dir if none found
- fix typos
- move comments over the lines instead of sideways. ]
Originally-from: Borislav Petkov <bp@alien8.de>
Suggested-by: Dave Hansen <dave.hansen@intel.com>
Suggested-by: Borislav Petkov <bp@alien8.de>
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lkml.kernel.org/r/1614928878-86075-1-git-send-email-feng.tang@intel.com
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.