AM486DX2 datasheet(5/67 Pages) AMD

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AMD

PRELIMINARY

Am5X86 Microprocessor

4.8.9 BOFF During Write-Back ..................................................................................................... 32

4.8.10 Snooping Characteristics During a Cache Line Fill ........................................................... 32

4.8.11 Snooping Characteristics During a Copy-Back ................................................................. 32

4.9 Cache Invalidation and Flushing in Write-Back mode .................................................................. 33

4.9.1 Cache Invalidation through Software .................................................................................. 33

4.9.2 Cache Invalidation through Hardware ................................................................................. 33

4.9.3 Snooping During Cache Flushing ........................................................................................ 34

4.10 Burst Write .................................................................................................................................. 34

4.10.1 Locked Accesses .............................................................................................................. 35

4.10.2 Serialization ....................................................................................................................... 35

4.10.3 PLOCK Operation in Write-Through mode ........................................................................ 36

Clock Control ...................................................................................................................................... 36

5.1 Clock Generation .......................................................................................................................... 36

5.2 Stop Clock ..................................................................................................................................... 36

5.2.1 External Interrupts in Order of Priority ................................................................................. 36

5.3 Stop Grant Bus Cycle ................................................................................................................... 36

5.4 Pin State during Stop Grant .......................................................................................................... 37

5.5 Clock Control State Diagram ........................................................................................................ 37

5.5.1 Normal State ........................................................................................................................ 37

5.5.2 Stop Grant State .................................................................................................................. 37

5.5.3 Stop Clock State .................................................................................................................. 39

5.5.4 Auto Halt Power Down State ............................................................................................... 39

5.5.5 Stop Clock Snoop State (Cache Invalidations) .................................................................... 39

5.5.6 Cache Flush State ............................................................................................................... 39

SRESET Function ............................................................................................................................... 39

System Management mode ................................................................................................................ 39

7.1 Overview ....................................................................................................................................... 39

7.2 Terminology .................................................................................................................................. 40

7.3 System Management Interrupt Processing ................................................................................... 40

7.3.1 System Management Interrupt Processing ......................................................................... 41

7.3.2 SMI Active (SMIACT) .......................................................................................................... 41

7.3.3 SMRAM ............................................................................................................................... 42

7.3.4 SMRAM State Save Map .................................................................................................... 43

7.4 Entering System Management mode ............................................................................................ 44

7.5 Exiting System Management mode .............................................................................................. 44

7.6 Processor Environment ................................................................................................................. 44

7.7 Executing System Management mode Handler ............................................................................ 45

7.7.1 Exceptions and Interrupts with System Management mode ............................................... 46

7.7.2 SMM Revisions Identifier ..................................................................................................... 46

7.7.3 Auto HALT Restart .............................................................................................................. 47

7.7.4 I/O Trap Restart ................................................................................................................... 47

7.7.5 I/O Trap Word ...................................................................................................................... 47

7.7.6 SMM Base Relocation ......................................................................................................... 48

7.8 SMM System Design Considerations ........................................................................................... 48

7.8.1 SMRAM Interface ................................................................................................................ 48

7.8.2 Cache Flushes .................................................................................................................... 49

7.8.3 A20M Pin ............................................................................................................................. 49

7.8.4 CPU Reset during SMM ...................................................................................................... 52

7.8.5 SMM and Second Level Write Buffers ................................................................................ 52

7.8.6 Nested SMI and I/O Restart ................................................................................................ 52

7.9 SMM Software Considerations ..................................................................................................... 52

7.9.1 SMM Code Considerations ................................................................................................. 52

7.9.2 Exception Handling ............................................................................................................. 52

7.9.3 Halt during SMM .................................................................................................................. 53

7.9.4 Relocating SMRAM to an Address above 1 Mbyte ............................................................. 53

AM486DX2 数据表(PDF) 5 Page - Advanced Micro Devices

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