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not return an INTR/IDENT Status Return packet. Figure 6-17 shows the
INTR/IDENT Status Return packet.
Figure 6-17
INTR/IDENT Status Return Packet
Clock cycle
31
0 0 0 0
1
Table 6-18 gives the description of the INTR/IDENT Status Return packet.
Table 6-18 INTR/IDENT Status Return Packet Description
Field
Description
Are always zero.
Clock 1, <31:20>
Interrupt priority level of the interrupt request. Bits <19:16> correspond
Clock 1, <19:16>
to IPL17 to IPL14, respectively. Only one IPL bit will be set per packet.
Are always zero.
Clock 1, <15:14>
The I/O port drives DND<13:12> of a INTR/IDENT Status Return packet
Clock 1, <13:12>
with 00 to indicate the packet type to the I/O adapter.
Clock 1, <11:0>
Are always zero.
Sparse Window Read Command Packet
The Sparse Window Read Command packet is used by processors to read
control and status registers in adapters on remote I/O buses that support
direct I/O window space.
The data for a Sparse Window Read Command packet is returned to the
I/O port on the Up Hose through a Sparse Window Read Data Return
packet. Figure 6-18 shows the Sparse Window Read Command packet.
Figure 6-18
Sparse Window Read Command Packet
Clock cycle
31 30 29
0 0
VID
1
Zero
2
Table 6-19 gives the description of the Sparse Window Read Command
packet.
DND <31:0>
20
19
0 0 0 0
0 0 0
DND <31:0>
27
26 25
Zero
16
15
IPL
0 0 0 0
0 0 0 0
15 14 13 12 11
0
1 1
Zero
Byte Aligned Address <26:0>
0
0 0 0 0 0 0 0 0
BXB-0643-93
4
3
2
1
0
LEN
SPC
BXB-0571-94
I/O Port 6-45
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