Intel
®
81341 and 81342 I/O Processors
December 2007
Developer’s Manual
Order Number: 315037-002US
829
Inter-Processor Messaging Unit—Intel
®
81341 and 81342
13.4.1
Interrupt Prioritization
The IMU provides a fixed priority scheme for servicing the 23 Interrupt Status bits in
the DBCR
For the eight Circular Queue Attention bits (DBCR[23:16]), the 4-bit Highest Priority
Circular Queue Attention field (DBCR[27:24]) represents the lowest order bit set.
For the Doorbell Status field of the DBCR[14:0], the 4-bit Highest Priority Door Bell
field (DBCR[31:28]) represents the lowest order bit set.
The two fixed priority schemes are detailed in
.
Table 506. Fixed Priority Scheme for Door Bell Status bits and Circular Queue Attention
Bits
Priority
Door Bell Status Bit Set Highest Priority Door
Bell Field
Circular
Attention Bit
Set
Highest
Priority
Circular
Queue
Attention
Field
Highest
DBSTAT0
0h
SQ0NF
0h
.............
DBSTAT1
1h
RQ0NE
1h
.............
DBSTAT2
2h
SQ1NF
2h
.............
DBSTAT3
3h
RQ1NE
3h
.............
DBSTAT4
4h
SQ2NF
4h
.............
DBSTAT5
5h
RQ2NE
5h
.............
DBSTAT6
6h
SQ3NF
6h
.............
DBSTAT7
7h
RQ3NE
7h
.............
DBSTAT8
8h
-
-
.............
DBSTAT9
9h
-
-
.............
DBSTAT10
Ah
-
-
.............
DBSTAT11
Bh
-
-
.............
DBSTAT12
Ch
-
-
.............
DBSTAT13
Dh
-
-
Lowest
DBSTAT14
Eh
-
-
-
None
Fh
None
Fh