1.

SMM OVERVIEW

Pages

9

1.1 Introduction . . .... . ... ... .. . . . ... . ... .. ... .... . ... ... .. . . .

9

1.2 SGS Thomson SMM Features . . . . . . . . . . . . . . . . . . . . . . . . .... . . . . ... .

9

1.3 A Typical SMM Routine . . . . . . . . . . . . . . . . . . . . . . . . . .... ... . . . . . . . 10

2.

SGS THOMSON SMM IMPLEMENTATION

13

2.1 Hardware Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ... ... .. ... 13

2.2 Configuration Control Registers . . . . . . . . . . . . ... ... .. ... ... .. . . . ... . 14

2.3 SMM Instruction Summary . . . . . . . . . . . . . . . . . . . ... ... .. ... ... .. . . . 18

3. SMM SOFTWARE CONSIDERATIONS

23

3.1 Enabling SMM . . . . . ... ... .. ... ... .. . . . ... . ... . . ... ... .. ... 23

3.2 SMM Handler Entry State . . . . . . . . . . . . . . . . . . . . . . .... . . . . ... . ... . 24

3.3 Maintaining the CPU State . . . . . . . . . . . . . . . ... ... .. ... ... .. . . . ... . 28

3.4 Initializing the SMM Environment . . . . . . . . . . . . . . . . . . . . . . . . .... ... . . . 31

3.5 Accessing Main Memory Overlapped by SMM Memory . . . . . . . ... ... .. ... ... . 32

3.6 I/O Restart

. . . . . . . . . . . . . . . . . . . . . . .... . . . . ... . ... . ... . ... . 33

3.7 I/O Port Shadowing and Emulation

. . . . . . . . . . . . . . . . . . . . . . . . . .... . ... 34

3.8 Return to HLT Instruction . . . . . . . . . . . . . . . . . . . . . . .... . . . . ... . ... . 35

3.9 Exiting the SMI Handler . . . .... . ... ... .. . . . ... . ... .. ... .... . . . . 37

3.10 Testing and Debugging SMM Code . . . .... ... . . . . . . . . . . . . . ... . ... . . . 38

4.

POWER MANAGEMENT FEATURES

41

4.1 Reducing the Clock Frequency . . . . . . . . . . . . . ... ... .. ... ... .. . . . ... . 41

4.2 Lowering the CPU Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . ... ... .. ... 41

4.3 Suspend Mode . . . . .... . ... ... .. . . . ... . ... .. ... .... . ... ... . 42

Appendix A

Assembler Macros for SGS Thomson Instructions

45

GENERAL INDEX

5