Mips Technologies R4000 - Page 403

MIPS R4000 Microprocessor User's Manual 373
System Interface
Figure 12-49 Snoop Request SysCmd Bus Bit Definition
Table 12-24 Encodings of SysCmd(4:0) for Snoop Requests
SysCmd(4) Processor Unacknowledged Update Cancellation
0 Update cancelled
1 No cancellation
SysCmd(3) Reserved
SysCmd(2:0) Cache State Change Function
0 No change to cache state
1
If cache state is clean exclusive, change to shared state;
otherwise make no change to cache state
2
If cache state is clean exclusive or shared, change to
invalid state; otherwise make no change to cache state
3
If cache state is clean exclusive, change to shared; if
cache state is dirty exclusive, change to dirty shared;
otherwise make no change to cache state
4
If cache state is clean exclusive, dirty exclusive, or
dirty shared, change to shared; otherwise make no
change to cache state
5 Change to invalid regardless of current cache state
6 Reserved
7 Reserved
111
0
8 7 5 4 03 2
Snoop Request Specific
(see table)