Pentium F00F Bug
Pentium OverDrive, P5 (Microarchitecture), Halt and Catch Fire]
Herausgegeben: Aristotle, Jacob
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The invalid operand with locked CMPXCHG8B instruction bug, commonly referred to as the Pentium F00F bug (as shorthand for f0 0f c7 c8, the hexadecimal encoding of one offending instruction),[1] is a design flaw in the majority of Intel Pentium, Pentium MMX, and Pentium OverDrive processors (all in the P5 microarchitecture). Under normal circumstances, this instruction would simply result in an exception; however, when used with the lock prefix (normally used to prevent two processors from interfering with the same memory location), the exception handler is never called, the processor stops ser...
The invalid operand with locked CMPXCHG8B instruction bug, commonly referred to as the Pentium F00F bug (as shorthand for f0 0f c7 c8, the hexadecimal encoding of one offending instruction),[1] is a design flaw in the majority of Intel Pentium, Pentium MMX, and Pentium OverDrive processors (all in the P5 microarchitecture). Under normal circumstances, this instruction would simply result in an exception; however, when used with the lock prefix (normally used to prevent two processors from interfering with the same memory location), the exception handler is never called, the processor stops servicing interrupts and the CPU must be reset to recover. The instruction does not require any special privileges and, due to the proliferation of Intel microprocessors, was considered a serious issue at the time. Operating system vendors responded by implementing workarounds that detected the condition and prevented the crash.
