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GICC_AIAR, CPU Interface Aliased Interrupt Acknowledge Register

The GICC_AIAR characteristics are:


Provides the INTID of the signaled Group 1 interrupt. A read of this register by the PE acts as an acknowledge for the interrupt.


When GICD_CTLR.DS==0, this register is an alias of the Non-secure view of GICC_IAR. A Secure access to this register is identical to a Non-secure access to GICC_IAR.


GICC_AIAR is a 32-bit register.

Field descriptions

The GICC_AIAR bit assignments are:


Bits [31:24]

Reserved, RES0.

INTID, bits [23:0]

The INTID of the signaled interrupt.


INTIDs 1020-1023 are reserved and convey additional information such as spurious interrupts.

When affinity routing is not enabled:

  • Bits [23:13] are RES0.
  • For SGIs, bits [12:10] identify the CPU interface corresponding to the source PE. For all other interrupts these bits are RES0.

Accessing the GICC_AIAR

When affinity routing is enabled for a Security state, it is a programming error to use memory-mapped registers to access the GIC.

GICC_AIAR can be accessed through the memory-mapped interfaces:

GIC CPU interface0x0020GICC_AIAR

This interface is accessible as follows:

  • When GICD_CTLR.DS == 0 accesses to this register are RO.
  • When an access is Secure accesses to this register are RO.
  • When an access is Non-secure accesses to this register are RO.