Intel 460GX 6.11.4.2.2 GART Interface Errors, 6.11.4.2.3 AGP Interface Errors, 6.11.4.2.4 Data Errors

Data Integrity and Error Handling

6.11.4.2.2 GART Interface Errors

•GART Parity Error - There is one parity bit covering each GART entry. When the GART is accessed, parity is checked. If an error occurs, then this bit is set. Parity errors are only reported when the access falls within the GART aperture range. This prevents errors being reported when the GART entry was not used.

•GART Entry Invalid - Each GART entry has a valid bit associated with it. If the GART entry associated with an AGP address is not marked as valid, then this bit is set. This error is only reported when the access falls within the GART aperture range. This prevents errors being reported when the GART entry was not used.

•Illegal Address - After translation is done, the address is checked. If it is in the range between GAPBAS and GAPTOP, or in the VGA range with VGAGE asserted, or directed by the MARG’s to PCI instead of memory, or above TOM; then the access is illegal and considered a fault.

•Illegal Outbound GART Access - Any programming access, read or write, to the GART that is not 4B or is not aligned on a 4B boundary. The behavior is undefined for the error.

6.11.4.2.3 AGP Interface Errors

•Use of Pipe with Sideband Enabled - The card must not mix sideband and Pipe requests. If sideband is enabled and the card attempts an access with PIPE, this error occurs.

•AGP Address[63:40] not Equal to Zero - This address is outside the legal graphics aperture and is over the TOM, therefore is an error.

•AGP Request Queue Overflow - The GXB supports 16 AGP transactions. If the card attempts to do a new transaction when there are 16 already outstanding, this error is flagged.

Illegal AGP Command - Set whenever the GXB receives an unknown or undefined command from the graphics card.

6.11.4.2.4 Data Errors

•AGP Hi-priority Write Que Data Parity Error - AGP write data was placed in the que with good parity. If this error is set, then the write que itself was corrupted. The GXB will not report this error with either interrupt or BINIT#. The error is actually reported by the SAC or allowed to continue to memory where it will be poisoned.

•AGP Low-priority Write Que Data Parity Error - AGP write data was placed in the que with good parity. If this error is set, then the write que itself was corrupted. The GXB will not report this error with either interrupt or BINIT#. The error is actually reported by the SAC or allowed to continue to memory where it will be poisoned.

•PCI Inbound Write Que Data Parity Error - PCI write data was placed in the que with parity as received from the PCI bus. This error may have occurred because of bad parity on the PCI bus or because the que itself was corrupted. The GXB will not report this error with either interrupt or BINIT#. The error is actually reported by the SAC or allowed to continue to memory where it will be poisoned.

Note: On data transfers from the card to the GXB, there may be wait states. If there is a parity error on the AD bus when there is a wait state, then the GXB will not flag any error. It only flags an error when data is actually captured by the GXB’s PCI interface.

•PCI Outbound Read Que Data Parity Error - PCI read data was placed in the que with parity as received from the PCI bus. The GXB will not report this error with either interrupt or BINIT#. The error is actually reported by the SAC or allowed to continue to memory where it will be poisoned.

6-24 Intel® 460GX Chipset Software Developer’s Manual