Datasheet

Functional Description
Intel® Xeon® Processor D-1500 Product Family 131
Datasheet - Volume 1 of 4: Integrated Platform Controller Hub
March 2015
Mapping Option #2 (Standard Option)
In this case, the Legacy Replacement Rout bit (LEG_RT_CNF) is 0. Each timer has its
own routing control. The interrupts can be routed to various interrupts in the 8259 or
I/O APIC. A capabilities field indicates which interrupts are valid options for routing. If a
timer is set for edge-triggered mode, the timers should not be shared with any legacy
interrupts.
For Intel® Xeon® Processor D-1500 Product Family, the only supported interrupt
values are as follows:
Timer 0 and 1: IRQ20, 21, 22 & 23 (I/O APIC only).
Timer 2: IRQ11 (8259 or I/O APIC) and IRQ20, 21, 22 & 23 (I/O APIC only).
Timer 3: IRQ12 (8259 or I/O APIC) and IRQ 20, 21, 22 & 23 (I/O APIC only).
Interrupts from Timer 4, 5, 6, 7 can only be delivered using processor message
interrupts.
Mapping Option #3 (Processor Message Option)
In this case, the interrupts are mapped directly to processor messages without going to
the 8259 or I/O (x) APIC. To use this mode, the interrupt must be configured to edge-
triggered mode. The Tn_PROCMSG_EN_CNF bit must be set to enable this mode.
When the interrupt is delivered to the processor, the message is delivered to the
address indicated in the Tn_PROCMSG_INT_ADDR field. The data value for the write
cycle is specified in the Tn_PROCMSG_INT_VAL field.
Notes:
1. The processor message interrupt delivery option has HIGHER priority and is
mutually exclusive to the standard interrupt delivery option. Thus, if the
Tn_PROCMSG_EN_CNF bit is set, the interrupts will be delivered directly to the
processor, rather than using the APIC or 8259.
The processor message interrupt delivery can be used even when the legacy mapping
is used.
3.16.3 Periodic versus Non-Periodic Modes
Non-Periodic Mode
Timer 0 is configurable to 32 (default) or 64-bit mode, whereas whereas Timers 1:7
only support 32-bit mode (See Section 14.1.5).
All of the timers support non-periodic mode.
Refer to Section 2.3.9.2.1 of the IA-PC HPET Specification for a description of this
mode.
Periodic Mode
Timer 0 is the only timer that supports periodic mode. Refer to Section 2.3.9.2.2 of the
IA-PC HPET Specification for a description of this mode.