FUJITSU Implementation Supplement Fujitsu SPARC64 V User Manual

Page 110

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Release 1.0, 1 July 2002

F. Chapter F

Memory Management Unit

99

TABLE F-6

describes the field encoding for

ISFSR.FT

.

Data <15>

TM

R/W

Translation miss. When

TM

= 1, it signifies an occurrence of a mITLB miss

upon an instruction reference.

Data <13:7>

FT

<6:0>

R/W

Fault type. Saves and indicates an exact condition that caused the recorded
exception. See

TABLE F-6

for the field encoding.

In the IMMU,

FT

is valid only for an

instruction_access_exception

. The

ISFSR.FT

always reads as 0 for a

fast_instruction_access_MMU_miss

and

reads 01

16

for an

instruction_access_exception

, since no other fault types

apply.

Data <5:4>

CT

<1:0>

R/W

Context type; Saves the context attribute for the reference that invokes an
exception. For nontranslating ASI or invalid ASI,

ISFSR.CT

= 11

02

.

00

02

:

Primary

01

02

:

Reserved

10

02

:

Nucleus

11

02

:

Reserved

Data <3>

PR

R/W

Privileged. Indicates the CPU privilege status during the instruction
reference that generates the exception. This field is valid when

ISFSR.FV

= 1.

Data <1>

OW

R/W

Overwritten. Set when

ISFSR.FV

= 1 upon the detection of a exception.

This means that the fault valid bit is not yet cleared when another fault is
detected.

Data <0>

FV

R/W

Fault valid. Set when the IMMU detects an exception. The bit is not set on
an IMMU miss. When the Fault Valid bit is not set, the values of the
remaining fields in the

ISFSR

are undefined, except for an IMMU miss.

TABLE F-6

Instruction Synchronous Fault Status Register

FT

(Fault Type) Field

FT<6:0>

Error Description

01

16

Privilege violation. Set when

TTE.P

= 1 and

PSTATE.PRIV

= 0 for the

instruction reference.

02

16

Reserved

04

16

Reserved

08

16

Reserved

10

16

Reserved

20

16

Reserved, since there is no virtual hole.

40

16

Reserved, since there is no virtual hole.

TABLE F-5

I

-SFSR

Bit Description

Bits

Field Name

RW

Description

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