Intel 925 Data Sheet - Page 44
CONFIG_DATA-Configuration Data Register, I/O Address, 0CFCh, Default Value, Access
UPC - 683728067724
View all Intel 925 manuals
Add to My Manuals
Save this manual to your list of manuals |
Page 44 highlights
Register Description R Bit 15:11 10:8 7:2 1:0 Access & Default R/W 00h R/W 000b R/W 00h Description Device Number: This field selects one agent on the PCI bus selected by the Bus Number. When the Bus Number field is "00", the MCH decodes the Device Number field. The MCH is always Device Number 0 for the Host bridge entity, Device Number 1 for the Host-PCI Express entity. Therefore, when the Bus Number =0 and the Device Number equals 0, 1, or 2 the internal MCH devices are selected. This field is mapped to byte 6 [7:3] of the request header format during PCI Express Configuration cycles and A [15:11] during the DMI configuration cycles. Function Number: This field allows the configuration registers of a particular function in a multi-function device to be accessed. The MCH ignores configuration cycles to its internal devices if the function number is not equal to 0 or 1. This field is mapped to byte 6 [2:0] of the request header format during PCI Express Configuration cycles and A[10:8] during the DMI configuration cycles. Register Number: This field selects one register within a particular Bus, Device, and Function as specified by the other fields in the Configuration Address Register. This field is mapped to byte 7 [7:2] of the request header format during PCI Express Configuration cycles and A[7:2] during the DMI Configuration cycles. Reserved 3.4.2 CONFIG_DATA-Configuration Data Register I/O Address: Default Value: Access: Size: 0CFCh 00000000h R/W 32 bits CONFIG_DATA is a 32-bit read/write window into configuration space. The portion of configuration space that is referenced by CONFIG_DATA is determined by the contents of CONFIG_ADDRESS. Bit Access & Default Description 31:0 R/W Configuration Data Window (CDW): If bit 31 of CONFIG_ADDRESS is 1, any 0000 0000h I/O access to the CONFIG_DATA register will produce a configuration transaction using the contents of CONFIG_ADDRESS to determine the bus, device, function, and offset of the register to be accessed. § 44 Intel® 82925X/82925XE MCH Datasheet