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IBM21P100BGB
IBM 133 PCI-X Bridge R1.1
ppb11_pcix_regs.fm.03
July 9, 2001
Configuration Registers
Page 67 of 131
5.2.5.9 Secondary Retry Counter Register
The Secondary Retry Counter register defines the number of retries that the bridge will receive on the
secondary bus for a requested transaction, before its internal retry counter expires. When the counter
expires, the bridge discards the request, and, if enabled, issues SERR# on the primary bus.
This mechanism prevents deadlock when the target is unable to receive the request, and allows recovery
through the use of SERR#.
The only allowed values are:
x‘0000 0000’: Counting disabled (No expiration)
x‘0000 0100’: 256 retries before expiration
x‘0001 0000’: 64K retries before expiration
x‘0100 0000’: 16M retries before expiration
x‘8000 0000’: 2G retries before expiration
Address Offset
x‘64’
Access
Read/Write
Reset Value
x‘0000 0000’
Restrictions
Only one bit can be set at any given time; setting multiple bits results in the
smaller retry count.
2G
re
tr
ies
Reserved
16M
ret
ri
e
s
Reserved
6
4
K
ret
ri
es
Reserved
2
5
6
ret
ries
Reserved
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10
9
8
7
6
5
4
3
2
1
0
Bit(s)
Access
Field Name and Description
31
RW
This bit used to indicate 2G retries before expiration
30:25
RO
Reserved
24
RW
This bit used to indicate 16M retries before expiration
23:17
RO
Reserved
16
RW
This bit used to indicate 64K retries before expiration
15:9
RO
Reserved
8
RW
This bit used to indicate 256 retries before expiration
7:0
RO
Reserved