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Embedded AMD Processor Recognition
63
23913A/0—November 2000
Embedded AMD-K6™ Processors BIOS Design Guide
Preliminary Information
Identifying Supported Features
The feature bits are returned in the EDX register for two
CPUID functions—standard function 1 and extended function
8000_0001h. Each bit corresponds to a specific feature and
indicates if that feature is present on the processor. Table 30
summarizes the standard and extended feature bits.
Table 30. Standard and Extended Feature Bits
Bit
1
Feature
Description
Standard
2
Extended
2
0
Floating-Point Unit
A floating-point unit is available.
1
1
1
Virtual Mode Extensions
Virtual mode extensions are available.
1
1
2
Debugging Extensions
I/O breakpoint debug extensions are supported.
1
1
3
PSE (Page Size Extensions)
4-Mbyte pages are supported.
1
1
4
Time Stamp Counter
(with RDTSC and CR4 disable bit)
A time stamp counter is available in the processor,
and the RDTSC instruction is supported.
1
1
5
K86™ Family of Processors’
Model-Specific Registers (with
RDMSR and WRMSR)
The K86 model-specific registers are available in the
processor, and the RDMSR and WRMSR instructions
are supported.
1
1
6
PAE (Page Address Extensions)
Page address extensions are supported using an
8-byte directory entry.
1
1
7
MCE (Machine Check Exception)
The machine check exception is supported.
1
1
8
CMPXCHG8B Instruction
The CMPXCHG8B instruction is supported.
1
1
9
APIC
A local APIC unit is available.
1
1
10
Reserved on all AMD processors
0
0
11
SYSENTER/SYSEXIT Instructions
The SYSENTER and SYSEXIT instructions are
supported.
1
0
SYSCALL and SYSRET Instructions
The SYSCALL and SYSRET instructions and
associated extensions are supported.
0
1
12
MTRR (Memory Type Range
Registers)
Memory type range registers are available.
1
1
13
Global Paging Extension
Global paging extensions are available.
1
1
14
MCA (Machine Check Architecture) Machine check architecture is supported
1
1
15
Conditional Move Instructions
The conditional move instructions CMOV, FCMOV,
and FCOMI are supported.
1
1
16
PAT (Page Attribute Table)
The Page attribute tables are supported.
1
1
17
PSE-36 (Page Size Extension)
Page size extensions for 36-bit addresses are
supported using a 4-byte directory entry.
1
1
18–21
Reserved on all AMD processors
0
0
22
AMD Multimedia Instruction
Extensions
AMD additions to the original MMX™ instruction set
are supported.
3
0
1