@startuml
'https://plantuml.com/sequence-diagram

title Apic::enable()

participant Apic
participant Acpi
participant LocalApic
participant IoApic
participant ApicErrorHandler
participant ApicTimer

==Prepare Initialization==

group Create Devices
Apic -[hidden]> ApicTimer
    Apic -> Acpi: Request system information
    Apic <- Acpi: Provide MADT structures
    Apic -> LocalApic ++: Instantiate LocalApic
    Apic -> IoApic ++: Instantiate IoApic
end

group Initialize Local APIC
Apic -[hidden]> ApicTimer
    Apic -> LocalApic: Enable xApic mode
    LocalApic -> LocalApic: Set IMCR
    LocalApic -> LocalApic: MMIO allocation
==Actual Component Initialization==
    Apic -> LocalApic: Initialize current local APIC
    LocalApic -> LocalApic: Set LVT and NMI
    LocalApic -> LocalApic: Set spurious vector
    LocalApic -> LocalApic: Synchronize APR
    LocalApic -> LocalApic: Allow all priorities
end

group Initialize I/O APIC
Apic -[hidden]> ApicTimer
    Apic -> IoApic: Initialize I/O APIC
    IoApic -> IoApic: MMIO allocation
    IoApic -> IoApic: Set REDTBL, NMI
end

group Initialize APIC error handler
Apic -[hidden]> ApicTimer
    Apic -> ApicErrorHandler ++: Instantiate handler
    Apic -> ApicErrorHandler: Register the interrupt handler
    Apic -> LocalApic: Allow current error interrupt
    Apic -> LocalApic: Arm error interrupt
end

group Initialize APIC timer
Apic -[hidden]> ApicTimer
    Apic -> ApicTimer: Calibrate the timer
    Apic -> ApicTimer ++: Instantiate current timer
    Apic -> ApicTimer: Register current interrupt handler
    LocalApic <- ApicTimer: Allow current timer interrupt
end
@enduml