Programmer’s Model 
ARM DDI0198D Copyright © 2001-2003 ARM Limited. All rights reserved. 2-19
The FSR accessed is determined by the value of the Opcode_2 field:
Opcode_2 = 0  Data Fault Status Register (DFSR).
Opcode_2 = 1  Instruction Fault Status Register (IFSR).
The fault type encoding is listed in Table 3-9 on page 3-22.
You can access the FSRs using the following instructions:
MRC p15, 0, <Rd>, c5, c0, 0 ;read DFSR
MCR p15, 0, <Rd>, c5, c0, 0 ;write DFSR
MRC p15, 0, <Rd>, c5, c0, 1 ;read IFSR
MCR p15, 0, <Rd>, c5, c0, 1 ;write IFSR
The format of the Fault Status Register is shown in Figure 2-8.
Figure 2-8 FSR format
Table 2-15 shows the bit field descriptions for the FSR. 
UNP/SBZ
31 9 8 7 4 3 0
0 Domain Status
Table 2-15 FSR bit field descriptions
Bits Description
[31:9] UNP/SBZP.
[8]  Always reads as zero. Writes ignored.
[7:4]  Specifies which of the 16 domains (D15-D0) was being 
accessed when a data fault occurred.
[3:0] Type of fault generated (see Table 2-16 on page 2-20).