For more information, see ACPI namespace hierarchy.įor each device described in the ACPI namespace hierarchy, the Windows ACPI driver, Acpi.sys, creates either a filter device object (filter DO) or a physical device object (PDO). The hardware platform vendor specifies a hierarchy of ACPI namespaces in the ACPI BIOS to describe the hardware topology of the platform. Microsoft ACPI source language (ASL) compiler Other tasks performed by Acpi.sys on a particular hardware platform might include reprogramming the resources for a COM port or enabling the USB controller for system wake-up. Acpi.sys is transparent to the other drivers in the device tree.

Acpi.sys acts as the interface between the operating system and the ACPI BIOS. On hardware platforms that have an ACPI BIOS, the HAL causes Acpi.sys to be loaded during system startup at the base of the device tree. The responsibilities of Acpi.sys include support for power management and Plug and Play (PnP) device enumeration. The Windows ACPI driver, Acpi.sys, is an inbox component of the Windows operating system.

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