CPUID: Difference between revisions

When called with EAX = 0, CPUID returns the brand name in EBX, EDX and ECX. Writing these to memory in this order results in a 12-character string. These can be tested against known brands:

 

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/* Vendor-strings. */

#define CPUID_VENDOR_RISE "RiseRiseRise"

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Also, EAX is set to the maximum EAX value supported for CPUID calls, as not all queries are supported on all processors

Recent processors also use ECX for features (which form a different set), with which you should be very careful as some old CPUs return bogus information in this register.

 

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/* Flags. */

#define CPUID_FLAG_PBE 0x80000000 /* Pending Break Event. */

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== Using CPUID from GCC ==

CPUID can be invoked with various request codes (in eax) and will return values in general registers (much as a built-in service interrupt). The following code is made Public Domain out of Clicker's x86/cpu.h

 

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enum cpuid_requests {

}

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== See Also ==