Module apic 

Local APIC and I/O APIC support for x86_64.

Provides initialization and control of the Local APIC (interrupt delivery to the local CPU) and I/O APIC (external interrupt routing). This module is additive to the existing PIC (8259) setup – the PIC remains as a fallback while the APIC handles advanced interrupt routing.

The Local APIC is memory-mapped at 0xFEE0_0000 (identity-mapped by the bootloader). The I/O APIC is at 0xFEC0_0000 with indirect register access via IOREGSEL/IOWIN.

Register constants and hardware API methods define the complete Local APIC and I/O APIC register set per the Intel SDM. Unused items are retained for hardware reference completeness.

Structs

IoApic

I/O APIC controller.

LocalApic

Local APIC controller.

RedirectionEntry

Redirection table entry – represents a 64-bit I/O APIC routing entry.

Constants

APIC_TIMER_VECTOR

APIC timer interrupt vector (dedicated, separate from PIC timer at 32).

SCHED_WAKE_VECTOR

Scheduler wake IPI vector – sent to wake a remote CPU from idle to run a task.

TLB_SHOOTDOWN_VECTOR

TLB shootdown IPI vector – sent to remote CPUs to flush stale TLB entries.

Functions

calibrate_timer

Calibrate the APIC timer frequency using the PIT (8254) as a reference.

init

Initialize the Local APIC and I/O APIC.

is_initialized

Check whether the APIC subsystem has been initialized.

is_timer_active

Check whether the APIC timer is active.

mask_irq

Mask an IRQ in the I/O APIC.

read_id

Read the Local APIC ID of the current CPU.

send_eoi

Send an End-Of-Interrupt to the Local APIC.

send_init_ipi

Send INIT IPI to a target CPU for AP startup sequence.

send_ipi

Send an Inter-Processor Interrupt via the Local APIC.

send_ipi_all_excluding_self

Broadcast an IPI to all CPUs except self. Used for TLB shootdown.

send_startup_ipi

Send Startup IPI (SIPI) to a target CPU for AP startup sequence.

set_irq_route

Route an external IRQ through the I/O APIC to a specific interrupt vector and destination CPU.

setup_timer

Configure the Local APIC timer for periodic interrupts.

start_timer

Start the APIC timer in periodic mode at approximately freq_hz Hz.

stop_timer

Stop the Local APIC timer.

ticks_per_ms

Get calibrated APIC timer ticks per millisecond.

unmask_irq

Unmask an IRQ in the I/O APIC.