Western Digital T13/2132-D - Manual (Page 63)

June 23, 2010 T13/2132-D Revision 3
Working Draft Enhanced Disk Drive - 4 (EDD-4) 51
8.20.3 Device Path
The Device Path at offset 56 combined with the Interface Path allows software external to a system BIOS to
locate a specific mass storage device. The Device Path field provides a path from an interface to a specific
device. The format of the Device Path at offset 40 through 47 is dependent on the Interface type.
PCI-X 48 Byte PCI-X bus number. Values 00h through FEh shall represent a valid PCI bus.
Value FFh shall indicate that this field is not used.
49 Byte PCI slot number. Values 00h through FEh shall represent a valid PCI slot.
Value FFh shall indicate that this field is not used.
50 Byte PCI function number. Values 00h through FEh shall represent a valid PCI
function.
Value FFh shall indicate that this field is not used.
51 Byte Channel number. If more than one interface of the same type is accessed
through a single Bus, Slot, Function, then the channel number shall identify
each interface. If there is only one interface, the content of this field shall be
cleared to zero. If there are two interfaces, such as an ATA Primary and
Secondary interface, the primary interface shall be zero, and the secondary
interface shall be one.
Values 00h through FEh shall represent a valid Channel Number.
Value FFh shall indicate that this field is not used.
If the device is connected to a SATA controller functioning in non-PATA
emulation mode, this byte shall be FFh.
52 DWord Reserved
Infiniband 48h Qword Reserved
PCI Express 48h Qword See PCI
HyperTransport 48h Qword See PCI
Table 23 — Interface Path Definitions (part 2 of 2)
Host Bus Type Offset Type Definition