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Some platforms, e.g. Alder Lake, have hybrid architecture. Although most PMU capabilities are the same, there are still some unique PMU capabilities for different hybrid PMUs. Perf should register a dedicated pmu for each hybrid PMU. Add a new struct x86_hybrid_pmu, which saves the dedicated pmu and capabilities for each hybrid PMU. The architecture MSR, MSR_IA32_PERF_CAPABILITIES, only indicates the architecture features which are available on all hybrid PMUs. The architecture features are stored in the global x86_pmu.intel_cap. For Alder Lake, the model-specific features are perf metrics and PEBS-via-PT. The corresponding bits of the global x86_pmu.intel_cap should be 0 for these two features. Perf should not use the global intel_cap to check the features on a hybrid system. Add a dedicated intel_cap in the x86_hybrid_pmu to store the model-specific capabilities. Use the dedicated intel_cap to replace the global intel_cap for thse two features. The dedicated intel_cap will be set in the following "Add Alder Lake Hybrid support" patch. Add is_hybrid() to distinguish a hybrid system. ADL may have an alternative configuration. With that configuration, the X86_FEATURE_HYBRID_CPU is not set. Perf cannot rely on the feature bit. Add a new static_key_false, perf_is_hybrid, to indicate a hybrid system. It will be assigned in the following "Add Alder Lake Hybrid support" patch as well. Suggested-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Kan Liang <kan.liang@linux.intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/1618237865-33448-5-git-send-email-kan.liang@linux.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.