B2.53 ESR_EL1, Exception Syndrome Register, EL1

The ESR_EL1 holds syndrome information for an exception taken to EL1.

Bit field descriptions

ESR_EL1 is a 32-bit register, and is part of the Exception and fault handling registers functional group.

Figure B2-39 ESR_EL1 bit assignments
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EC, [31:26]
Exception Class. Indicates the reason for the exception that this register holds information about.
IL, [25]

Instruction Length for synchronous exceptions. The possible values are:

0 16-bit.
1 32-bit.

This field is 1 for the SError interrupt, instruction aborts, misaligned PC, Stack pointer misalignment, data aborts for which the ISV bit is 0, exceptions caused by an illegal instruction set state, and exceptions using the 0x00 Exception Class.

ISS, [24:0]

Syndrome information.

When reporting a virtual SEI, bits[24:0] take the value of VSESRL_EL2[24:0].

When reporting a physical SEI, the following occurs:

  • IDS==0 (architectural syndrome).
  • AET always reports an uncontainable error (UC) with value 0b000 or an unrecoverable error (UEU) with value 0b001.
  • EA is RES0.

When reporting a synchronous data abort, EA is RES0.

See B2.108 VSESR_EL2, Virtual SError Exception Syndrome Register.


This register has no configuration options.

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