IRQ
2
Via SERIRQ
Via PCI
Message
System Resource
20
N/A
Yes
Option for SCI, TCO, HPET #0, 1, 2, 3. Other internal devices
are routable.
21
N/A
22
N/A
23
N/A
1. PIRQ is not externally routed rather they are used to reference internally routed PCIe* interrupts.
2. When programming the polarity of internal interrupt sources on the APIC, interrupts 0 through 15 receive
active-high internal interrupt sources, while interrupts 16 through 23 receive active-low internal interrupt
sources
3. If IRQ 11 is used for HPET #2, software should ensure IRQ 11 is not shared with any other devices to
guarantee the proper operation of HPET #2. The hardware does not prevent sharing of IRQ 11.
4. If IRQ 12 is used for HPET #3, software should ensure IRQ 12 is not shared with any other devices to
guarantee the proper operation of HPET #3. The hardware does not prevent sharing of IRQ 12.
Table 29.
PCH GPIO Mapping
Signal
Name
I/O
Type
Default
Mode
Ball
Coun
t
Default
Direction
and Logic
State
Power
Well
Internal/
External
Resistor Pull-
Up/Down
Description
BMBUSY#
/GPI0
I/O
GPI
1
I
CORE
CORE
Bus Master Busy. This signal is used to
support the C3 state. It indicates that a
bus master device is busy.
When this signal is asserted, the BM_STS
bit will be set. If this signal goes active in
a C3 state, it is treated as a break event.
This signal is internally synchronized
using the PCICLK and a two-stage
synchronizer. It does not need to meet
any particular setup or hold time. This
signal can also be used as GPIO Port 0.
GPIO1
I/O
GPI
1
I
CORE
General Purpose I/O Port 1. Not
Multiplexed.
GPIO2
1
I/O
GPI
1
I
CORE
General Purpose I/O Port 2. Not
Multiplexed.
GPIO3
1
I/O
GPI
1
I
CORE
General Purpose I/O Port 3. Not
Multiplexed.
GPIO4
1
I/O
GPI
1
I
CORE
General Purpose I/O Port 4. Not
Multiplexed.
GPIO5
1
I/O
GPI
1
I
CORE
General Purpose I/O Port 5. Not
Multiplexed.
GPIO6
I/O
GPI
1
I
CORE
General Purpose I/O Port 6. Not
Multiplexed.
GPIO7
I/O
GPI
1
I
CORE
General Purpose I/O Port 1. Not
Multiplexed.
GPIO8
I/O
GPO
1
O (High)
SUS
Weak Internal
pull-up for strap
General Purpose I/O Port 8. Not
Multiplexed. This signal has a weak
internal pull-up and must not be pulled
low at boot up
GPIO9
2
I/O
Native
1
I
SUS
General Purpose I/O Port 9. Not
Multiplexed
3
continued...
Technical Reference—Crystal Forest
Intel
®
Xeon
®
Processor E3-1125C with Intel
®
Communications Chipset 8910 Development Kit
October 2012
User Guide
Order No.: 328009-001US
45