
Agere Systems Inc.
165
Data Sheet
May 2001
and Packet Payload Engine
Ambassador T8110 PCI-Based H.100/H.110 Switch
14
Connection Control—Standard and Virtual Channel
(continued)
14.2.3.5.1 System Errors Due to Packet Switching
The system error indicators for packet switch activity are located in the system error register, 0x00126. These indi-
cators are inputs to the interrupt controller, and are maskable interrupts. There are eight indicators, as shown
below.
Table 117. System Error Register Address 0x00126
BIT
Mnemonic
Description
7
PMFOB
PCI master, fatal error
—this bit is set when a T8110-initiated PCI cycle results in abnormal
termination, including the following:
n
Requested PCI target does not respond (master abort).
n
Requested PCI target terminates (target abort).
n
Requested PCI target responds with PCI_DEVSEL#, but does not follow with
PCI_TRDY# or PCI_STOP# to allow the cycle to complete (PCI_TRDY# time-out, see
Table 12 on page 34).
n
Requested PCI target retries beyond the retry count (RETRY time-out, see Table 12 on
page 34).
PCI master, external buffer LOCK error—this bit is set when a T8110 descriptor table fetch
indicates the
USER
has locked the external buffer, and T8110 access to the external buffer
is denied.
PCI master, external buffer STALL error—this bit is set when a T8110 descriptor table fetch
indicates that there is a pointer boundary condition (end-of-buffer, or T8110 pointer has
caught up to
USER
pointer), and T8110 access to the external buffer is denied.
PCI master, external buffer STALL error—this bit is set when a T8110 descriptor table fetch
indicates that there is only one external buffer access left before a pointer boundary condi-
tion (end-of-buffer, or T8110 pointer has caught up to
USER
pointer). T8110 access to the
external buffer is allowed.
PCI master, external buffer OVERWRITE warning—this bit is set when a T8110 descriptor
table fetch indicates the
USER
has enabled the T8110 to overwrite unread data in the
external buffer (i.e., override a boundary condition). This is applicable for
push
operation
only.
PCI master, external buffer INITIAL warning—this bit is set when a T8110 descriptor table
fetch indicates the
USER
has not written anything into the external buffer (the initial state of
a
pull
operation).
Virtual channel memory, scratchpad OVERFLOW warning—indicates the calculated
scratchpad current depth has exceeded the overall buffer depth (VC programming error).
NOTIFY_QUEUE OVERFLOW warning—indicates that a request to
push
(or
pull
) a
packet of data did not occur within one frame time (125 us), and T8110's internal data
buffer will get overwritten (
push
) or contain stale data (
pull
).
6
PMLOB
5
PMEOB
4
PMWOB
3
PMOOB
2
PMIOB
1
VCOOB
0
NQOOB