Datasheet 429
PCI-to-PCI Bridge Registers (D30:F0)
11.1.22 BPS—Bridge Proprietary Status Register
(PCI-PCI—D30:F0)
Offset Address: 48h–4Bh Attribute: R/WC, RO
Default Value: 00000000h Size: 32 bits
Bit Description
31:17 Reserved
16
PERR# Assertion Detected (PAD) — R/WC. This bit is set by hardware whenever the
PERR# pin is asserted on the rising edge of PCI clock. This includes cases in which the
chipset is the agent driving PERR#. It remains asserted until cleared by software
writing a 1 to this location. When enabled by the PERR#-to-SERR# Enable bit (in the
Bridge Policy Configuration register), a 1 in this bit can generate an internal SERR# and
be a source for the NMI logic.
This bit can be used by software to determine the source of a system problem.
15:7 Reserved
6:4
Number of Pending Transactions (NPT) — RO. This read-only indicator tells debug
software how many transactions are in the pending queue. Possible values are:
000 = No pending transaction
001 = 1 pending transaction
010 = 2 pending transactions
011 = 3 pending transactions
100 = 4 pending transactions
101 = 5 pending transactions
110–111 = Reserved
NOTE: This field is not valid if DTC.MDT (offset 44h:bits 7:6) is any value other than
‘00’.
3:2 Reserved
1:0
Number of Active Transactions (NAT) — RO. This read-only indicator tells debug
software how many transactions are in the active queue. Possible values are:
00 = No active transactions
01 = 1 active transaction
10 = 2 active transactions
11 = Reserved
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