Vol. 3 10-45
ADVANCED PROGRAMMABLE INTERRUPT CONTROLLER (APIC)
ICR in xAPIC mode, except the Delivery Status bit is removed since it is not needed
in x2APIC mode. The destination ID field is expanded to 32 bits in x2APIC mode.
To send an IPI, software must set up the ICR or SELF IPI register to indicate the type
of IPI message to be sent and the destination processor or processors.
A single MSR write to the Interrupt Command Register is required for dispatching an
interrupt in x2APIC mode. With the removal of the Delivery Status bit, system soft-
ware no longer has a reason to read the ICR. It remains readable only to aid in
debugging.
A destination ID value of FFFF_FFFFH is used for broadcast of interrupts in both
logical destination and physical destination modes.
Figure 10-18. Interrupt Command Register (ICR) in x2APIC Mode
31 0
Reserved
7
Vector
Destination Shorthand
810
Delivery Mode
000: Fixed
001: Reserved
00: No Shorthand
01: Self
111213141516171819
10: All Including Self
11: All Excluding Self 010: SMI
011: Reserved
100: NMI
101: INIT
110: Start Up
111: Res erved
Destination Mode
0: Physical
1: Logical
Level
0 = De-assert
1 = Assert
Trigger Mode
0: Edge
1: Level
63 32
Destination Field
Address: 830H (63 - 0)
Value after Reset: 0H
Reserved
20