82801CA Datasheet, PDF (120/521 Pages) Intel Corporation – I/O Controller Hub 3-S (ICH3-S)

Functional Description
Remote Read Message
Remote read message is used when a local APIC wishes to read the register in another local APIC.
The I/O APIC in the ICH3 neither generates or responds to this cycle. The message format is same
as short message for the first 21 cycles.
Table 5-24. Remote Read Message
Cycle
1
2–5
6
Bit 1
1
ARBID
NOT(DM)
Bit 0
0
1
NOT(M2)
7
NOT(M1)
NOT(M0)
8
NOT(L)
NOT(TM)
9
NOT(V7)
NOT(V6)
10
NOT(V5)
NOT(V4)
11
NOT(V3)
NOT(V2)
12
NOT(V1)
NOT(V0)
13
NOT(D7)
NOT(D6)
14
NOT(D5)
NOT(D4)
15
NOT(D3)
NOT(D2)
16
NOT(D1)
NOT(D0)
17
NOT(C1)
NOT(C0)
18
1
1
19
NOT(A)
NOT(A)
20
NOT(A1)
NOT(A1)
21
d31
d30
22
d29
d28
23
d27
d26
24
d25
d24
25
d23
d22
26
d21
d20
27
d19
d18
28
d17
d16
29
d15
d14
30
d13
d12
31
d11
d10
32
d09
d08
33
d07
d06
34
d05
d04
35
d03
d02
36
d01
d00
37
S
S
38
C
C
39
1
1
Comments
Normal Arbitration
Arbitration ID
DM = Destination Mode from bit 11 of the redirection table register
M2–M0 = Delivery Mode from bits 10:8 of the redirection table
register
L = Level, TM = Trigger Mode
Interrupt vector bits V7–V0 from redirection table register
Destination field from bits 63:56 of redirection table register
Checksum for Cycles 6–16
Postamble
Status Cycle 0.
Status Cycle 1.
Remote register data 31–0
Data Status: 00 = valid, 11 = invalid
Check Sum for data d31–d00
Idle
NOTE: Cycle 21 through 36 contain the remote register data. The status information in cycle 37 specifies if the
data is good or not. Remote read cycle is always successful (although the data may be valid or invalid)
in that it is never retried. The reason for this is that Remote Read is a debug feature, and a “hung”
remote APIC that is unable to respond should not cause the debugger to hang.
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Intel^® 82801CA ICH3-S Datasheet