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Embedded AMD Processor Recognition
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23913A/0—November 2000
Embedded AMD-K6™ Processors BIOS Design Guide
Preliminary Information
Embedded AMD Processor Recognition
The CPUID instruction provides a simple way for hardware and
software to identify the type of processor and its feature set.
After detecting the processor and its capabilities, software can
be accurately tuned to the system for optimal performance and
benefit to users.
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For example, game software can test the performance level
available from a particular processor by detecting the type
or speed of the processor. If the features warrant executing
additional capabilities or advanced algorithms, these can be
enabled with software.
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Another example involves testing for the presence of
3DNow! or MMX instructions on the processor. If the
software finds these features present when it checks the
feature bits, it can utilize these more powerful extensions
for dramatically better performance on new multimedia
software.
See http://www.amd.com/products/cpg/bin for example software
and source code to detect processor information.
CPUID Instruction Overview
Software operating at any privilege level can execute the
CPUID instruction to identify the processor and its feature set.
In addition, the CPUID instruction implements multiple
functions, each providing different information about the
processor, including the vendor, model number, revision
(stepping), features, cache organization, and processor name.
The multiple-function approach allows the CPUID instruction
to return a complete picture about the type of processor and its
capabilities — more detailed information than could be
returned by a single function. The CPUID instruction provides
the flexibility of making only one call to obtain the specific data
requested.
The functions are divided into two types: standard functions
and extended functions.