Intel 460GX manual Multiple Errors, GXB Error Flow

Data Integrity and Error Handling

•PCI Outbound Write Que Data Parity Error - This error signifies that either a) data was received from the Expander bus with bad parity or b) the OB write Que was corrupted. As data is read from the queue and passed to the PCI bus, the parity is checked.

•AGP Low-priority Read Data Que Parity Error - This error signifies that either a) data was received from the Expander bus with bad parity or b) the read Que was corrupted. As data is read from the queue and passed to the AGP bus, the parity is checked.

•AGP Hi-priority Read Data Que Parity Error - This error signifies that either a) data was received from the Expander bus with bad parity or b) the read Que was corrupted. As data is read from the queue and passed to the AGP bus, the parity is checked.

•PCI Inbound Read Que Data Parity Error - This error signifies that either a) data was received from the Expander bus with bad parity or b) the read Que was corrupted. As data is read from the queue and passed to the AGP bus, the parity is checked. This is for PCI reads done by the graphics card. The parity on the PCI data will be poisoned out to the card as the data is returned.

6.11.4.3Multiple Errors

In the case that 2 or more errors occur at the same cycle, multiple bits are set in the FERR register. This should be an extremely rare case. Software can read the register and check that only one bit is set. The data that is captured along with the error is indeterminate. Since there are multiple registers for error data, 2 errors may cause the Expander and PCI error registers to have valid data. Or, if there were 2 errors from Expander bus at the same time, then the Expander data-error register may have been set by either error.

Figure 6-3. GXB Error Flow

SAC Interconnect

SAC

SAC

Check parity.

UpS

DnS

On HDR: BINIT#. Drop

SAC

Data

PKT and data. Set FERR.

Data

IB

Pass data to SAC with

parity from queue, don’t

Place data into buffer

check outgoing parity.

with parity as received from

Expander (16 data, 2 BE, 1 par.)

SAC

OB

PCI

AGP

AGP

IB

LO

HI

AGP

AGP

PCI

PCI

High

Low

IB

OB

Write

Write

Write

Read

Data

Data

Data

Data

GART

Chk parity.

PCI

AGP

AGP

IB

Low

High

AGP

AGP

PCI

PCI

Generate parity

High

Low

IB

OB

in Expander format,

CFG

PCI

Read

Read

Read

Write

Ctrl

OB

Data

Data

Data

Data

data and BE. If

PCI data is bad,

poison into

AGP

Check Parity.

buffer.

Que

If PCI, then corrupt outgoing parity.

SRAM

AGP Bus

Intel® 460GX Chipset Software Developer’s Manual 6-25