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The _OSC method allows the OS and firmware to communicate about supported features/capabitlities. It also allows the OS to take control of some features. In ACPI 6.4, s6.2.11.2 Platform-Wide OSPM Capabilities, the CPPC (resp. v2) bit should be set by the OS if it 'supports controlling processor performance via the interfaces described in the _CPC object'. The OS supports CPPC and parses the _CPC object only if CONFIG_ACPI_CPPC_LIB is set. Replace the x86 specific boot_cpu_has(X86_FEATURE_HWP) dynamic check with an arch generic CONFIG_ACPI_CPPC_LIB build-time check. Note: CONFIG_X86_INTEL_PSTATE selects CONFIG_ACPI_CPPC_LIB. Signed-off-by: Pierre Gondois <pierre.gondois@arm.com> Reviewed-by: Sudeep Holla <sudeep.holla@arm.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@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.