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Exception Syndrome Register, EL3

The ESR_EL3 characteristics are:


Holds syndrome information for an exception taken to EL3.

Usage constraints

This register is accessible as follows:








(SCR.NS = 1)


(SCR.NS = 0)

- - - - RW RW

ESR_EL3 is mapped to AArch32 register DFSR(S). See Data Fault Status Register.


ESR_EL3 is a 32-bit register.

Figure 4.54 shows the ESR_EL3 bit assignments.

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Table 4.102 shows the ESR_EL3 bit assignments.

Table 4.102.  ESR_EL3 bit assignments
Bits Name Function
[31:26] EC Exception Class. Indicates the reason for the exception that this register holds information about.
[25] IL

Instruction Length for synchronous exceptions. The possible values are:





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 0x0 Exception Class.

[24] ISS Valid

Syndrome valid. The possible values are:


ISS not valid, ISS is res0.


ISS valid.

[23:0] ISS

Syndrome information.

When the EC field is 0x2F, indicating an SError interrupt has occurred, the ISS field contents are IMPLEMENTATION DEFINED. Table 4.103 shows the definition of the ISS field contents for the Cortex-A53 processor.

Table 4.103. ISS field contents for the Cortex-A53 processor
ISS[23:22] ISS[1:0] Description
0b00 0b00

DECERR on external access

0b00 0b01

Double-bit error detected on dirty line in L2 cache

0b00 0b10

SLVERR on external access

0b01 0b00

nSEI, or nVSEI in a guest OS, asserted

0b01 0b01

nREI asserted

To access the ESR_EL3:

MRS <Xt>, ESR_EL3 ; Read EL3 Exception Syndrome Register
MSR ESR_EL3, <Xt> ; Write EL3 Exception Syndrome Register
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