Filter
Top Products
Protocols — Console Support
Version 1.10 12/01/02 10-51
10.11 EFI Simple Pointer Device Paths
An EFI_SIMPLE_POINTER_PROTOCOL must be installed on a handle for its services to be
available to EFI Drivers and EFI Applications. In addition to the
EFI_SIMPLE_POINTER_PROTOCOL, an EFI_DEVICE_PATH
must also be installed on the
same handle. See Chapter 5 of the EFI Specification for detailed description of the
EFI_DEVICE_PATH.
A device path describes the location of a hardware component in a system from the processor’s
point of view. This includes the list of busses that lie between the processor and the pointer
controller. The EFI Specification takes advantage of the ACPI Specification to name system
components. The following set of examples shows sample device paths for a PS/2
†
mouse, a serial
mouse, and a USB mouse.
Table 10-5 shows an example device path for a PS/2 mouse that is located behind a PCI to ISA
bridge that is located at PCI device number 0x07 and PCI function 0x00, and is directly attached to
a PCI root bridge. This device path consists of an ACPI Device Path Node for the PCI Root
Bridge, a PCI Device Path Node for the PCI to ISA bridge, an ACPI Device Path Node for the PS/2
mouse, and a Device Path End Structure. The _HID and _UID of the first ACPI Device Path Node
must match the ACPI table description of the PCI Root Bridge. The shorthand notation for this
device path is:
ACPI(PNP0A03,0)/PCI(7|0)/ACPI(PNP0F03,0)
Table 10-5. PS/2 Mouse Device Path
Byte
Offset
Byte
Length
Data
Description
0x00 0x01 0x02 Generic Device Path Header – Type ACPI Device Path
0x01 0x01 0x01 Sub type – ACPI Device Path
0x02 0x02 0x0C Length – 0x0C bytes
0x04 0x04 0x41D0,
0x0A03
_HID PNP0A03 – 0x41D0 represents a compressed string ‘PNP’ and is in
the low order bytes.
0x08 0x04 0x0000 _UID
0x0C 0x01 0x01 Generic Device Path Header – Type Hardware Device Path
0x0D 0x01 0x01 Sub type – PCI
0x0E 0x02 0x06 Length – 0x06 bytes
0x10 0x01 0x00 PCI Function
0x11 0x01 0x07 PCI Device
continued