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GICC_AHPPIR, CPU Interface Aliased Highest Priority Pending Interrupt Register

The GICC_AHPPIR characteristics are:

Purpose

If the highest priority pending interrupt is in Group 1, this register provides the INTID of the highest priority pending interrupt on the CPU interface.

Configuration

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

Attributes

GICC_AHPPIR is a 32-bit register.

Field descriptions

The GICC_AHPPIR bit assignments are:

313029282726252423222120191817161514131211109876543210
00000000INTID

Bits [31:24]

Reserved, RES0.

INTID, bits [23:0]

The INTID of the signaled interrupt.

Note

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_AHPPIR

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

  • For AArch32 implementations, ICC_HPPIR1 provides equivalent functionality.
  • For AArch64 implementations, ICC_HPPIR1_EL1 provides equivalent functionality.

If the highest priority pending interrupt is in Group 0, a read of this register returns the special INTID 1023.

Interrupt identifiers corresponding to an interrupt group that is not enabled are ignored.

If the highest priority pending interrupt is a direct interrupt that is both individually enabled in the Distributor and part of an interrupt group that is enabled in the Distributor, and the interrupt group is disabled in the CPU interface for this PE, this register returns the special INTID 1023.

See Preemption for more information about pending interrupts that are not considered when determining the highest priority pending interrupt.

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

GICC_AHPPIR can be accessed through the memory-mapped interfaces:

ComponentOffsetInstance
GIC CPU interface0x0028GICC_AHPPIR

This interface is accessible as follows:

  • When GICD_CTLR.DS == 0b0 access to this register is RO.
  • When IsAccessSecure() access to this register is RO.
  • When !IsAccessSecure() access to this register is RO.


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