Power Saving Features
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18524C/0—Nov1996
AMD-K5 Processor Technical Reference Manual
A.5.4
SMM Save Area
The contents of any reserved locations are not necessarily the
same between the AMD-K5 and Pentium processors. In addi-
tion, the AMD-K5 and the Pentium processors store the IDT
base at different locations in the SMM save area. The AMD-K5
processor stores the IDT base at offset 7F94h, and the Pentium
processor stores it at offset 7F90h. These locations were previ-
ously reserved but are now documented in current Pentium
processor documentation.
A.5.5
NMI Recognition during SMM
When operating in SMM, an NMI request should not be recog-
nized unless an enabled INTR is encountered. Both the
AMD-K5 and Pentium processors do this correctly, but in
slightly different ways. The Pentium processor takes the NMI
request immediately after recognizing the INTR, but before
executing any instructions from the interrupt handler. The
AMD-K5 processor takes the NMI request upon encountering
the IRET in the interrupt handler. (In fact, the AMD-K5 pro-
cessor unmasks NMI when any IRET is encountered, not just
one associated with INTR.)
Comment
With both processors, the Intel recommendation of using a
fake INTR to unmask NMI while in SMM works correctly.
Summary of Contents for AMD-K5
Page 1: ...AMD K5 Processor Technical Reference Manual TM...
Page 10: ...x AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 24: ...1 4 Overview AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 54: ...2 30 Internal Architecture AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 116: ...4 26 Performance AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 356: ...6 44 System Design AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 380: ...7 24 Test and Debug AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 396: ...A 16 AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...
Page 406: ...I 10 Index AMD K5 Processor Technical Reference Manual 18524C 0 Nov1996...