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+---
+page_type: sample
+description: "Demonstrates a simulated power policy device."
+languages:
+- cpp
+products:
+- windows
+- windows-wdk
+---
+
+# plpolicy - Simulated Power Limit Policy Driver
+
+This sample is a driver for a simulated power limit policy device.
+
+## Universal Windows Driver Compliant
+
+The plpolicy sample provides the source code for a power limit controller that supplies power limit management to the operating system.
+
+This driver supplies IOCTLs to receive commands from other modules and plumb cooresponding information to the hardware through OS kernel
+space APIs.
+
+IOCTL_POWERLIMIT_POLICY_REGISTER: Other module supplies the BIOS name of the target device to control the power limit.
+
+IOCTL_POWERLIMIT_POLICY_QUERY_ATTRIBUTES: Query the target device for supported power limits and attributes.
+
+IOCTL_POWERLIMIT_POLICY_QUERY_VALUES: Query the target device for active power limit values.
+
+IOCTL_POWERLIMIT_POLICY_SET_VALUES: Set power limit values to the target device.
+
+For a production driver, those IOCTLs are not needed. Instead, the policy driver should:
+1. During the init phase, subscribes to GUID_DEVINTERFACE_POWER_LIMIT notifications. Then query client's BIOS name in the callback, and
+   compares it with the target client device. Then create power limit request through PoCreatePowerLimitRequest, query attributes through
+   PoQueryPowerLimitAttributes.
+
+2. At runtime, the policy driver should collect input signals and calcualte power limit target(s), then send targets to the client through
+   PoSetPowerLimitValue. If necessary, the policy driver can query the current power limit of client through PoQueryPowerLimitValue.
+
+3. If the power limit control is no longer needed, delete the power limit request through PoDeletePowerLimitRequest.