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PMF Policy binary is a encrypted and signed binary that will be part of the BIOS. PMF driver via the ACPI interface checks the existence of Smart PC bit. If the advertised bit is found, PMF driver walks the acpi namespace to find out the policy binary size and the address which has to be passed to the TA during the TA init sequence. The policy binary is comprised of inputs (or the events) and outputs (or the actions). With the PMF ecosystem, OEMs generate the policy binary (or could be multiple binaries) that contains a supported set of inputs and outputs which could be specifically carved out for each usage segment (or for each user also) that could influence the system behavior either by enriching the user experience or/and boost/throttle power limits. Once the TA init command succeeds, the PMF driver sends the changing events in the current environment to the TA for a constant sampling frequency time (the event here could be a lid close or open) and if the policy binary has corresponding action built within it, the TA sends the action for it in the subsequent enact command. If the inputs sent to the TA has no output defined in the policy binary generated by OEMs, there will be no action to be performed by the PMF driver. Example policies: 1) if slider is performance ; set the SPL to 40W Here PMF driver registers with the platform profile interface and when the slider position is changed, PMF driver lets the TA know about this. TA sends back an action to update the Sustained Power Limit (SPL). PMF driver updates this limit via the PMFW mailbox. 2) if user_away ; then lock the system Here PMF driver hooks to the AMD SFH driver to know the user presence and send the inputs to TA and if the condition is met, the TA sends the action of locking the system. PMF driver generates a uevent and based on the udev rule in the userland the system gets locked with systemctl. The intent here is to provide the OEM's to make a policy to lock the system when the user is away ; but the userland can make a choice to ignore it. The OEMs will have an utility to create numerous such policies and the policies shall be reviewed by AMD before signing and encrypting them. Policies are shared between operating systems to have seemless user experience. Since all this action has to happen via the "amdtee" driver, currently there is no caller for it in the kernel which can load the amdtee driver. Without amdtee driver loading onto the system the "tee" calls shall fail from the PMF driver. Hence an explicit MODULE_SOFTDEP has been added to address this. Signed-off-by: Shyam Sundar S K <Shyam-sundar.S-k@amd.com> Link: https://lore.kernel.org/r/20231212014705.2017474-5-Shyam-sundar.S-k@amd.com Signed-off-by: Hans de Goede <hdegoede@redhat.com> |
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| init | ||
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| ipc | ||
| kernel | ||
| lib | ||
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| rust | ||
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| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
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| COPYING | ||
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| 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 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.