Digi NS9215 manual Fault a d d r e s s r e g i s t e r, Status and domain fields

Status and domain fields

WO R K I N G W I T H T H E C P U	. .
R6: Fault Address register..
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This table shows the encodings used for the status field in the Fault Status register, and indicates whether the domain field contains valid information. See “MMU faults and CPU aborts” on page 119 for information about MMU aborts in Fault Address and Fault Status registers.

Priority	Source	Size	Status	Domain
Highest	Alignment	N/A	0b00x1	Invalid
	External abort on translation	First level	0b1100	Invalid
		Second level	0b1110	Valid
	Translation	Section page	0b0101	Invalid
			0b0111	Valid
	Domain	Section page	0b1001	Valid
			0b1011	Valid
	Permission	Section page	0b1101	Valid
			0b1111	Valid
Lowest	External abort	Section page	0b1000	Valid
			0b1010	Valid

R 6 : F a u l t A d d r e s s r e g i s t e r

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Access instructions

Register R6 accesses the Fault Address register (FAR). The Fault Address register contains the modified virtual address of the access attempted when a data abort occurred. This register is updated only for data aborts, not for prefetch aborts; it is updated also for alignment faults and external aborts that occur while the MMU is disabled.

Writing R6 sets the Fault Address register to the value of the data written. This is useful for debugging, to restore the value of a Fault Address register to a previous state.

The CRm and opcode_2 fields SHOULD BE ZERO when reading or writing R6.

Use these instructions to access the Fault Address register:

MRC p15, 0, Rd, c6, c0, 0; read FAR

MCR p15, 0, Rd, c6, c0, 0; write FAR

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