Datasheet

Functional Description
R
Datasheet 161
Table 41. PCI Commands Supported by the GMCH When Acting as a FRAME# Target
GMCH
PCI Command C/BE[3:0]# Encoding
Cycle Destination
Response as A FRAME#
Target
Interrupt Acknowledge 0000 N/A No Response
Special Cycle 0001 N/A No Response
I/O Read 0010 N/A No Response
I/O Write 0011 N/A No Response
Reserved 0100 N/A No Response
Reserved 0101 N/A No Response
Memory Read 0110 Main Memory Read
0110 The Hub interface No Response
Memory Write 0111 Main Memory Posts Data
0111 The Hub interface No Response
Reserved 1000 N/A No Response
Reserved 1001 N/A No Response
Configuration Read 1010 N/A No Response
Configuration Write 1011 N/A No Response
Memory Read Multiple 1100 Main Memory Read
1100 The Hub interface No Response
Dual Address Cycle 1101 N/A No Response
Memory Read Line 1110 Main Memory Read
1110 The Hub interface No Response
Memory Write and
Invalidate
1111 Main Memory Posts Data
1111 The Hub interface No Response
NOTE: N/A refers to a function that is not applicable.
As a target of an AGP FRAME# cycle, the GMCH only supports the following transactions:
• Memory Read, Memory Read Line, and Memory Read Multiple. These commands are
supported identically by the GMCH. The GMCH does not support reads of the hub interface
bus from AGP.
• Memory Write and Memory Write and Invalidate. These commands are aliased and
processed identically. The GMCH does not support writes to the hub interface bus from
AGP.
• Other Commands. Other commands such as I/O R/W and Configuration R/W are not
supported by the GMCH as a target and result in master abort.
• Exclusive Access. The GMCH does not support PCI locked cycles as a target.