Specifications

I/O Port 6-45
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
Table 6-18 gives the description of the INTR/IDENT Status Return packet.
Table 6-18 INTR/IDENT Status Return Packet Description
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
Table 6-19 gives the description of the Sparse Window Read Command
packet.
31 20 19
15 0
000
000
0
0000
BXB-0643-93
DND <31:0>
1

Clock cycle
16
0000
IPL
0
0
0
0
0
0
0
0
0
0
0
0
Field Description
Clock 1, <31:20>
Are always zero.
Clock 1, <19:16>
Interrupt priority level of the interrupt request. Bits <19:16> correspond
to IPL17 to IPL14, respectively. Only one IPL bit will be set per packet.
Clock 1, <15:14>
Are always zero.
Clock 1, <13:12>
The I/O port drives DND<13:12> of a INTR/IDENT Status Return packet
with 00 to indicate the packet type to the I/O adapter.
Clock 1, <11:0>
Are always zero.
31 30 29 26 25 0
0 0 VID Zero Zero SPC
BXB-0571-94
1

2

Clock cycle
DND <31:0>
Byte Aligned Address <26:0>
15 14 13 12 11 12
110
34
LEN
27
Zero