Intel 64 and IA-32 Architectures Software Developers Manual Volume 3A, System Programming Guide, Part 1

Vol. 3A 8-15
ADVANCED PROGRAMMABLE INTERRUPT CONTROLLER (APIC)
returned in the Max LVT field is 5; for the P6 family processors
(which have 5 LVT entries), the value returned is 4; for the
Pentium processor (which has 4 LVT entries), the value returned
is 3.
8.5 HANDLING LOCAL INTERRUPTS
The following sections describe facilities that are provided in the local APIC for
handling local interrupts. These include: the processor’s LINT0 and LINT1 pins, the
APIC timer, the performance-monitoring counters, the thermal sensor, and the
internal APIC error detector. Local interrupt handling facilities include: the LVT, the
error status register (ESR), the divide configuration register (DCR), and the initial
count and current count registers.
8.5.1 Local Vector Table
The local vector table (LVT) allows software to specify the manner in which the local
interrupts are delivered to the processor core. It consists of the following five 32-bit
APIC registers (see Figure 8-8), one for each local interrupt:
• LVT Timer Register (FEE0 0320H) — Specifies interrupt delivery when the
APIC timer signals an interrupt (see Section 8.5.4, “APIC Timer”).
• LVT Thermal Monitor Register (FEE0 0330H) — Specifies interrupt delivery
when the thermal sensor generates an interrupt (see Section 13.4.2, “Thermal
Monitor”). This LVT entry is implementation specific, not architectural. If imple-
mented, it will always be at base address FEE0 0330H.
• LVT Performance Counter Register (FEE0 0340H) — Specifies interrupt
delivery when a performance counter generates an interrupt on overflow (see
Section 18.15.6.8, “Generating an Interrupt on Overflow”). This LVT entry is
implementation specific, not architectural. If implemented, it is not guaranteed
to be at base address FEE0 0340H.
• LVT LINT0 Register (FEE0 0350H) — Specifies interrupt delivery when an
interrupt is signaled at the LINT0 pin.
Figure 8-7. Local APIC Version Register
31
0
Reserved
2324 15
Version
Max. LVT
Value after reset: 000N 00VVH
V = Version, N = # of LVT entries minus 1
Entry
7
Address: FEE0 0030H
16 8
Reserved