Linux kernel source tree
d845cd901b
On some systems, the HWP (Hardware P-states) highest performance level can change from the value set at boot-up. This behavior can lead to two issues: - The 'cpuinfo_max_freq' within the 'cpufreq' sysfs will not reflect the CPU's highest achievable performance. - Even if the CPU's highest performance level is increased after booting, the CPU may not reach the full expected performance. The availability of this feature is indicated by the CPUID instruction: if CPUID[6].EAX[15] is set to 1, the feature is supported. When supported, setting bit 2 of the MSR_HWP_INTERRUPT register enables notifications of the highest performance level changes. Therefore, as part of enabling the HWP interrupt, bit 2 of the MSR_HWP_INTERRUPT should also be set when this feature is supported. Upon a change in the highest performance level, a new HWP interrupt is generated, with bit 3 of the MSR_HWP_STATUS register set, and the MSR_HWP_CAPABILITIES register is updated with the new highest performance limit. The processing of the interrupt is the same as the guaranteed performance change. Notify change to cpufreq core and update MSR_HWP_REQUEST with new performance limits. The current driver implementation already takes care of the highest performance change as part of: commit |
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| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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 reStructuredText 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.