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GICC_AEOIR, CPU Interface Aliased End Of Interrupt Register

The GICC_AEOIR characteristics are:


A write to this register performs priority drop for the specified Group 1 interrupt and, if the appropriate GICC_CTLR.EOImodeS or GICC_CTLR.EOImodeNS field == 0, also deactivates the interrupt.


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


GICC_AEOIR is a 32-bit register.

Field descriptions

The GICC_AEOIR 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_AEOIR

A write to this register must correspond to the most recently acknowledged Group 1 interrupt. If a value other than the last value read from GICC_AIAR is written to this register, the effect is UNPREDICTABLE.

This register is used only when System register access is not enabled. When System register access is enabled:

  • For AArch32 implementations, ICC_EOIR1 provides equivalent functionality.
  • For AArch64 implementations, ICC_EOIR1_EL1 provides equivalent functionality.

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

GICC_AEOIR can be accessed through the memory-mapped interfaces:

GIC CPU interface0x0024GICC_AEOIR

This interface is accessible as follows:

  • When GICD_CTLR.DS == 0b0 accesses to this register are WO.
  • When IsAccessSecure() accesses to this register are WO.
  • When !IsAccessSecure() accesses to this register are WO.