Intel 460GX - Manual (Page 123)

Intel® 460GX Chipset Software Developer’s Manual 6-25
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.
6.11.4.3 Multiple 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
AGP Bus
SAC
IB
SAC
UpS
Data
SAC
DnS
Data
CFG
Ctrl
SAC
OB
SRAM
SAC Interconnect
Check Parity.
If PCI, then corrupt outgoing parity.
Generate parity
in Expander format,
data and BE. If
Check parity.
On HDR: BINIT#. Drop
PKT and data. Set FERR.
PCI data is bad,
poison into
buffer.
Chk parity.
Place data into buffer
with parity as received from
Expander (16 data, 2 BE, 1 par.)
Pass data to SAC with
parity from queue, don’t
check outgoing parity.
GART
AGP
High
Read
Data AGP
Low
Read
Data PCI
IB
Read
Data PCI
OB
Write
Data
AGP
High
Write
Data AGP
Low
Write
Data PCI
IB
Write
Data PCI
OB
Read
Data
PCI
OB
PCI
IB AGP
LO AGP
HI
PCI
IB AGP
Low AGP
High
AGP
Que