CPUID: Difference between revisions
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The complete Intel algorithm is available in AP-485, or via anonymous FTP at ftp://ftp.intel.com/pub/IAL/tools_utils_demos/cpuid3.zip. | The complete Intel algorithm is available in AP-485, or via anonymous FTP at ftp://ftp.intel.com/pub/IAL/tools_utils_demos/cpuid3.zip. | ||
==CPUID and [[SMP|multiple processors]]== | ==CPUID and [[SMP on x86|multiple processors]]== | ||
Some CPUID attributes require multiple CPUID calls to retrieve (often EAX is first set to 0 to determine the highest attribute request supported, then called again with specific requests). Behavior is undefined if CPUID information from one processor is used to form requests for another (especially in a heterogeneous system). Furthermore, CPUID must be performed on each processor used -- results for one processor have no general ramifications for others (again, especially in a heterogeneous system). Thus, either: | Some CPUID attributes require multiple CPUID calls to retrieve (often EAX is first set to 0 to determine the highest attribute request supported, then called again with specific requests). Behavior is undefined if CPUID information from one processor is used to form requests for another (especially in a heterogeneous system). Furthermore, CPUID must be performed on each processor used -- results for one processor have no general ramifications for others (again, especially in a heterogeneous system). Thus, either: | ||
* the process using CPUID must be bound to a single CPU by the system administrator, | * the process using CPUID must be bound to a single CPU by the system administrator, | ||