FAULTS
8-11
8
A parallel fault handler must be accessed through a system-supervisor call. Local and system-local
parallel fault handlers are not supported by the architecture and have unpredictable behavior. Tracing
is disabled upon entry into the parallel fault handler (PC.te is cleared). It is restored upon return from
the handler. To prevent infinite internal loops, the parallel fault handler should not set PC.te.
8.6.4.2
Fault Record for Parallel Faults
When parallel faults occur, the processor selects one of the faults and records it in the first 16 bytes
of the fault record as described in
section 8.5.1, “Fault Record Description” (pg. 8-7)
. The
remaining parallel faults are written to the fault record’s optional section, and the fault handling
procedure for parallel faults is invoked.
Figure 8-3
shows the structure of the fault record for
parallel faults.
The OType/OSubtype word at NFP - 20 contains the number of parallel faults. The optional section
also contains a 32-byte parallel fault record for each additional parallel fault. These parallel fault
records are stored incrementally in the fault record starting at byte offset NFP-65. The fault record
for each additional fault contains only the fault type, fault subtype, address-of-faulting-instruction
and the optional fault section. (For example, if two parallel faults occur, the fault record for the
second fault is located from NFP-96 to NFP-65.)
To calculate byte offsets, “n” indicates the fault number. Thus, for the second fault recorded (n=2),
the relationship (NFP-4-(n * 32)) reduces to NFP-72. For the i960 Jx processor, a maximum of two
faults are reported in the parallel fault record, and one of them must be the
ARITHMETIC.INTEGER_OVERFLOW fault on a
muli
instruction.
8.6.5
Override Faults
The i960 Jx processor can detect a fault condition while the processor is preparing to service a
previously detected fault. When this occurs, it is called an override condition. This section
describes this condition and how the processor handles it.
A normal fault condition is handled by the processor in the following manner:
•
The current local registers are saved and cached on-chip.
•
PFP = FP and the value 001 is written to the Return Type Field (Fault Call). Refer to
section 7.8, “RETURNS” (pg. 7-20)
for more information.
•
If the fault call is a system-supervisor call from user mode, the processor switches to the
supervisor stack; otherwise, SP is re-aligned on the current stack.
•
The processor writes the fault record on the new stack.
•
The IP of the first instruction of the fault handler is accessed through the fault table or through
the system procedure table (for system fault calls).
Содержание i960 Jx
Страница 1: ...Release Date December 1997 Order Number 272483 002 i960 Jx Microprocessor Developer s Manual ...
Страница 24: ......
Страница 25: ...1 INTRODUCTION ...
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Страница 35: ...2 DATA TYPES AND MEMORY ADDRESSING MODES ...
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Страница 47: ...3 PROGRAMMING ENVIRONMENT ...
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Страница 73: ...4 CACHE AND ON CHIP DATA RAM ...
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Страница 85: ...5 INSTRUCTION SET OVERVIEW ...
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Страница 111: ...6 INSTRUCTION SET REFERENCE ...
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Страница 195: ...INSTRUCTION SET REFERENCE 6 83 6 Opcode mov 5CCH REG movl 5DCH REG movt 5ECH REG movq 5FCH REG See Also LOAD STORE lda ...
Страница 233: ...7 PROCEDURE CALLS ...
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Страница 257: ...8 FAULTS ...
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Страница 291: ...9 TRACING AND DEBUGGING ...
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Страница 309: ...10 TIMERS ...
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Страница 325: ...11 INTERRUPTS ...
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Страница 369: ...12 INITIALIZATION AND SYSTEM REQUIREMENTS ...
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Страница 413: ...13 MEMORY CONFIGURATION ...
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Страница 429: ...14 EXTERNAL BUS ...
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Страница 469: ...15 TEST FEATURES ...
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Страница 493: ...A CONSIDERATIONS FOR WRITING PORTABLE CODE ...
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Страница 503: ...B OPCODES AND EXECUTION TIMES ...
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Страница 515: ...C MACHINE LEVEL INSTRUCTION FORMATS ...
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Страница 523: ...D REGISTER AND DATA STRUCTURES ...
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Страница 551: ...GLOSSARY ...
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Страница 561: ...INDEX ...
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