Figure 1. Cpuid Instruction Flow Chart - AMD -K6-2/450 - MHz Processor Application Note

Embedded AMD-K6™ Processors BIOS Design Guide
Check for CPUID
instruction support
CPUID instruction
supported
Execute CPUID
Standard Function EAX=0
Store Vendor String
EAX > 1 ?
Execute CPUID
Standard Function EAX=1
Store returned Standard
Function Feature bits and
Processor Signature;
Determine MMX and,
optionally, SSE* support
Execute CPUID
Extended Function
EAX=8000_0000h to
determine number of
extended functions supported
* Streaming SIMD Extensions

Figure 1. CPUID Instruction Flow Chart

12
Preliminary Information
No CPUID instruction--
No
Use other means
to detect CPU type
Yes
No
AMD processor not
present—Check for
other CPU brands
Yes
Extended Functions
Not Supported
No
EAX >
8000_0001h ?
Execute CPUID
Extended Function
EAX=8000_0001h
Utilize Vendor String and
Extended Function Feature
bits to determine 3DNow!,
3DNow! Extensions, and
MMX™ Extensions support
Utilize Processor Signature to
determine MSR support
Execute CPUID
Extended Functions
EAX=8000_0002h,
8000_0003h,
and 8000_0004h
to display processor
name string
Execute CPUID
Extended Functions
EAX=8000_0005h and
EAX=8000_0006h (Model 9 &
Model D) to gather processor
cache and TLB information
Execute CPUID
Extended Function
EAX=8000_0007h (Model D)
to gather AMD PowerNow!
technology information for the
processor
Tune software to optimize
for features present
Yes
Done
CPUID Identification Algorithms
23913A/0—November 2000