Proberesponse Commands (Command[4:0] = 00001); Programming Set_Dirty_Enable[2:0]; Ev67 Proberesponse Command - Compaq 21264 Hardware Reference Manual

System Port
Table 4–16 Programming SET_DIRTY_ENABLE[2:0]
SET_DIRTY_ENABLE
[2,0] (DS,CS,C)
000
001
010
011
100
101
110
111
Systems that require an explicit indication of ChangeToDirty status changes initi-
ated by STx_C instructions can assert Cbox CSR STC_ENABLE[0]. When this
register field = 000, CleanToDirty and SharedToDirty commands are used. The dis-
tinction between a ChangeToDirty command generated by a STx_C instruction and
one generated by a STx instruction is important to systems that want to service
ChangeToDirty commands with dirty data from a source processor. In this case, the
distinction between a locked exclusive instruction and a normal instruction is criti-
cal to avoid livelock for a LDx_L/STx_C sequence.

4.7.5 ProbeResponse Commands (Command[4:0] = 00001)

The 21264/EV67 responds to system probes that did not miss with a 4-cycle transfer on
SysAddOut_L[14:0]. As shown in Table 4–14, the Command[4:0] field for a ProbeRe-
sponse command equals 00001. Table 4–17 shows the format of the 21264/EV67 Prob-
eResponse command.
Table 4–17 21264/EV67 ProbeResponse Command
Cycle 1 0 00001
Cycle 2
Cycle 3 0
Cycle 4
Cache and External Interfaces
4–24
Cbox Action
Everything acknowledged internally (uniprocessor).
Only clean blocks generate external acknowledge (CleanToDirty commands only).
Only clean/shared blocks generate external acknowledge (SharedToDirty command
only).
Clean and clean/shared blocks generate external acknowledge.
Only dirty/shared blocks generate external acknowledge (SharedToDirty commands
only).
Only dirty/shared and clean blocks generate external acknowledge.
Only dirty/shared and clean/shared blocks generate external acknowledge.
All transactions generate external acknowledge.
SysAddOut_L[14:2]
Status[1:0] DM VS
0 MS
X
X
SysAddOut_L[1] SysAddOut_L[0]
VDB X X
[2:0]
MAF X X
[2:0]
X
X
Alpha 21264/EV67 Hardware Reference Manual
X
X