Local APIC

Local Advanced Programmable Interrupt Controller. More...

Collaboration diagram for Local APIC:

Detailed Description

Local Advanced Programmable Interrupt Controller.

Local APICs

Each CPU has its own local APIC, which, when used with the IO APICs, allows for more advanced interrupt handling in comparison to the traditional PIC, such as routing interrupts to specific CPUs, interrupt prioritization, and more. Most of its features are not used in PatchworkOS yet.

Additionally, the local APICs provide Inter-Processor Interrupts (IPIs) which allow a CPU to interrupt another CPU by using its local APIC.

Note

Its a common mistake to assume that the local APIC IDs are contiguous, or that they are the same as the CPU IDs, but this is not the case. The local APIC IDs are assigned by the firmware and can be any value.

See also

ACPI Specification Version 6.6

Data Structures
struct	lapic_t
	Local APIC Structure. More...

Macros
#define	LAPIC_REG_ID_OFFSET   24
	The offset at which the lapic id is stored in the LAPIC_REG_ID register.

Typedefs
typedef uint8_t	lapic_id_t
	Local APIC ID type.

Enumerations
enum	lapic_msr_flags_t { LAPIC_MSR_ENABLE = 0x800 , LAPIC_MSR_BSP = 0x100 }
	Local APIC MSR Flags. More...
enum	lapic_register_t {   LAPIC_REG_ID = 0x020 , LAPIC_REG_VERSION = 0x030 , LAPIC_REG_TASK_PRIORITY = 0x080 , LAPIC_REG_ARBITRATION_PRIORITY = 0x090 ,   LAPIC_REG_PROCESSOR_PRIORITY = 0x0A0 , LAPIC_REG_EOI = 0x0B0 , LAPIC_REG_REMOTE_READ = 0x0C0 , LAPIC_REG_LOGICAL_DEST = 0x0D0 ,   LAPIC_REG_DEST_FORMAT = 0x0E0 , LAPIC_REG_SPURIOUS = 0x0F0 , LAPIC_REG_ISR_BASE = 0x100 , LAPIC_REG_TMR_BASE = 0x180 ,   LAPIC_REG_IRR_BASE = 0x200 , LAPIC_REG_ERROR_STATUS = 0x280 , LAPIC_REG_LVT_CMCI = 0x2F0 , LAPIC_REG_ICR0 = 0x300 ,   LAPIC_REG_ICR1 = 0x310 , LAPIC_REG_LVT_TIMER = 0x320 , LAPIC_REG_LVT_THERMAL = 0x330 , LAPIC_REG_LVT_PERFCTR = 0x340 ,   LAPIC_REG_LVT_LINT0 = 0x350 , LAPIC_REG_LVT_LINT1 = 0x360 , LAPIC_REG_LVT_ERROR = 0x370 , LAPIC_REG_TIMER_INITIAL_COUNT = 0x380 ,   LAPIC_REG_TIMER_CURRENT_COUNT = 0x390 , LAPIC_REG_TIMER_DIVIDER = 0x3E0 }
	Local APIC Registers. More...
enum	lapic_flags_t { LAPIC_SPURIOUS_ENABLE = (1 << 8) , LAPIC_LVT_MASKED = (1 << 16) }
	Local APIC Flags. More...
enum	lapic_icr_delivery_mode_t {   LAPIC_ICR_FIXED = (0 << 8) , LAPIC_ICR_LOWEST_PRIORITY = (1 << 8) , LAPIC_ICR_SMI = (2 << 8) , LAPIC_ICR_NMI = (4 << 8) ,   LAPIC_ICR_INIT = (5 << 8) , LAPIC_ICR_STARTUP = (6 << 8) }
	Local APIC ICR Delivery Modes. More...
enum	lapic_icr_flags_t { LAPIC_ICR_CLEAR_INIT_LEVEL = (1 << 14) }
	Local APIC ICR Flags. More...

Functions
void	lapic_init (cpu_t *cpu)
	Initialize the local APIC for a CPU.
uint32_t	lapic_read (uint32_t reg)
	Read from a local apic register.
void	lapic_write (uint32_t reg, uint32_t value)
	Write to a local apic register.
void	lapic_send_init (lapic_id_t id)
	Send an INIT IPI to the specified local APIC.
void	lapic_send_sipi (lapic_id_t id, void *entryPoint)
	Send a Startup IPI (SIPI) to the specified local APIC.
uint64_t	lapic_global_init (void)
	Global initialization for the local APICs.

Variables
lapic_t PERCPU	_pcpu_lapic
	The per-CPU local APIC structure.

Macro Definition Documentation

LAPIC_REG_ID_OFFSET

#define LAPIC_REG_ID_OFFSET   24

The offset at which the lapic id is stored in the LAPIC_REG_ID register.

Definition at line 83 of file lapic.h.

Typedef Documentation

lapic_id_t

typedef uint8_t lapic_id_t

Local APIC ID type.

Definition at line 34 of file lapic.h.

Enumeration Type Documentation

lapic_msr_flags_t

enum lapic_msr_flags_t

Local APIC MSR Flags.

Enumerator
LAPIC_MSR_ENABLE
LAPIC_MSR_BSP

Definition at line 40 of file lapic.h.

lapic_register_t

enum lapic_register_t

Local APIC Registers.

Enumerator
LAPIC_REG_ID
LAPIC_REG_VERSION
LAPIC_REG_TASK_PRIORITY
LAPIC_REG_ARBITRATION_PRIORITY
LAPIC_REG_PROCESSOR_PRIORITY
LAPIC_REG_EOI
LAPIC_REG_REMOTE_READ
LAPIC_REG_LOGICAL_DEST
LAPIC_REG_DEST_FORMAT
LAPIC_REG_SPURIOUS
LAPIC_REG_ISR_BASE
LAPIC_REG_TMR_BASE
LAPIC_REG_IRR_BASE
LAPIC_REG_ERROR_STATUS
LAPIC_REG_LVT_CMCI
LAPIC_REG_ICR0
LAPIC_REG_ICR1
LAPIC_REG_LVT_TIMER
LAPIC_REG_LVT_THERMAL
LAPIC_REG_LVT_PERFCTR
LAPIC_REG_LVT_LINT0
LAPIC_REG_LVT_LINT1
LAPIC_REG_LVT_ERROR
LAPIC_REG_TIMER_INITIAL_COUNT
LAPIC_REG_TIMER_CURRENT_COUNT
LAPIC_REG_TIMER_DIVIDER

Definition at line 50 of file lapic.h.

lapic_flags_t

enum lapic_flags_t

Local APIC Flags.

Enumerator
LAPIC_SPURIOUS_ENABLE
LAPIC_LVT_MASKED

Definition at line 89 of file lapic.h.

lapic_icr_delivery_mode_t

enum lapic_icr_delivery_mode_t

Local APIC ICR Delivery Modes.

Enumerator
LAPIC_ICR_FIXED
LAPIC_ICR_LOWEST_PRIORITY
LAPIC_ICR_SMI
LAPIC_ICR_NMI
LAPIC_ICR_INIT
LAPIC_ICR_STARTUP

Definition at line 99 of file lapic.h.

lapic_icr_flags_t

enum lapic_icr_flags_t

Local APIC ICR Flags.

Enumerator
LAPIC_ICR_CLEAR_INIT_LEVEL

Definition at line 113 of file lapic.h.

Function Documentation

lapic_init()

void lapic_init

(

cpu_t *

cpu

)

Initialize the local APIC for a CPU.

Parameters

cpu	The current CPU.

lapic_read()

uint32_t lapic_read

(

uint32_t

reg

)

Read from a local apic register.

Parameters

reg	The register to read from.

Returns

The value read from the register.

Definition at line 37 of file lapic.c.

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lapic_write()

void lapic_write	(	uint32_t	reg,
		uint32_t	value
	)

Write to a local apic register.

Parameters

reg	The register to write to.
value	The value to write.

Definition at line 42 of file lapic.c.

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lapic_send_init()

void lapic_send_init

(

lapic_id_t

id

)

Send an INIT IPI to the specified local APIC.

Sending an INIT IPI will cause the target CPU to enter the INIT state, preparing it for startup.

Parameters

id	The ID of the local APIC to send the INIT IPI to.

Definition at line 66 of file lapic.c.

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lapic_send_sipi()

void lapic_send_sipi	(	lapic_id_t	id,
		void *	entryPoint
	)

Send a Startup IPI (SIPI) to the specified local APIC.

Sending a SIPI will cause the target CPU to start executing code at the specified entry point address.

Parameters

id	The ID of the local APIC to send the SIPI to.
entryPoint	The entry point address for the SIPI, must be page-aligned.

Definition at line 72 of file lapic.c.

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lapic_global_init()

uint64_t lapic_global_init

(

void

)

Global initialization for the local APICs.

Returns

On success, 0. On failure, ERR and errno is set.

Definition at line 80 of file lapic.c.

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Variable Documentation

_pcpu_lapic

lapic_t PERCPU _pcpu_lapic

extern

The per-CPU local APIC structure.