Fujitsu Fujitsu SPARC64 V manual MMU Synchronous Fault Status Register FT Fault Type Field

TABLE F-9	MMU Synchronous Fault Status Register FT (Fault Type) Field (Continued)
FT<6:0>	Error Description
0816	An attempt was made to access an alternate address space with an illegal ASI
	value, an illegal VA, an invalid read/write attribute, or an illegally sized
	operand. If the quad load ASI is used with the other opcode than LDDA, this bit
	is set.
	Note: Since an illegal ASI check is done prior to a TTE unmatch check,
	DSFSR.FT<3> = 1 causes the value of other bits of DSFSR.FT to be
	undetermined and generates a data_access_exception exception (which
	otherwise has lower priority than fast_data_access_MMU_miss).
	Note, too, that a reference to an internal ASI may generate a
	mem_address_not_aligned exception.
1016	Access other than nonfaulting load was made to a page marked NFO. This bit is
	zero for internal ASI accesses.
2016	Reserved, since there is no virtual hole.
4016	Reserved, since there is no virtual hole.

Multiple bits of DSFSR.FT may be set by a trap as long as the cause of the trap matches multiply in TABLE F-9.

DSFSR is updated upon various traps, including fast_data_access_MMU_miss, data_access_exception, fast_data_access_protection, PA_watchpoint, VA_watchpoint, privileged_action, mem_address_not_aligned, and data_access_error traps. TABLE F-10shows the detailed update policy of each field.

TABLE F-10	DSFSR Update Policy
		Field	TLB#,	FV	OW	W, PR,	FT	TM	ASI	UE, UPA,	DSFAR
			index			NF, CT1				mDTLB, NC2, E2
				Fresh fault or miss3
Miss		MMU miss	—	0	0	V	—	1	—	—	V
Exception		Access exception	—	1	0	V	V	0	V	—	V
		Access protection	—	1	0	V	—	0	V	—	V
		PA watchpoint	—	1	0	V	—	0	V	—	V
Faults
		VA watchpoint	—	1	0	V	—	0	V	—	V
		Privileged action4	—	1	0	V	—	0	V	—	V
		Access misaligned	—	1	0	V	—	0	V	—-	V
		Access error	V5	1	0	V	—	0	V	V	V
				Overwrite Policy6
Exception on fault			K	1	1	U	U	K	U	K	U
Fault on exception			U4	1	1	U	K	K	U	U	U
Exception on miss7			K	1	K	U	U	1	U	K	U
Fault on miss			U4	1	K	U	K	1	U	U	U

Release 1.0, 1 July 2002 F. Chapter F Memory Management Unit 103