The value in ECX specifies one of the 64-bit Model Specific Registers of the Pentium processor. The contents of EDX:EAX is copied into that Model-Specific Register. The high-order 32 bits are copied from EDX and the low-order 32 bits are copied from EAX.
The following values are used to select model specific registers on the Pentium processor:
┌───────┬──────────────────────┬────────────────────────────────────────────────┐ │ VALUE │REGISTER NAME │DESCRIPTION │ ├───────┼──────────────────────┼────────────────────────────────────────────────┤ │ 00H │Machine Check Address │Stores address of cycle causing the exception │ ├───────┼──────────────────────┼────────────────────────────────────────────────┤ │ 01H │Machine Check Type │Stores cycle type of cycle causing the exception│ └───────┴──────────────────────┴────────────────────────────────────────────────┘
For other values used to perform cache, TLB, and BTB testing and performance monitoring, see the Intel documentation.