A Machine Check Exception (MCE) is a type of computer hardware error that occurs when a computer's central processing unit detects a hardware problem.
Microsoft Windows displays the error using the blue screen of death containing the error message (the parameters inside the brackets vary):
STOP: 0x0000009C (0x00000004, 0x00000000, 0xB2000000, 0x00020151) "MACHINE_CHECK_EXCEPTION"
On Linux, a process (such as klogd[1] ) writes a message to the kernel log and/or the console screen (usually only to the console when the error is non-recoverable and the machine crashes as a result):
CPU 0: Machine Check Exception: 0000000000000004 Bank 2: f200200000000863 Kernel panic: CPU context corrupt
The error usually occurs due to failure or overstressing of hardware components where the error cannot be more specifically identified with a different error message. Diagnosing the error message can be difficult, although Intel Pentium processors do generate more specific codes which can be decoded by contacting the manufacturer.
MCEs require a restart of the system before users can continue normal operation: they often indicate a long-term problem of a general nature.
Contents |
Most of these errors relate specifically to the Pentium processor family. Similar errors may occur on other processors and will cause similar problems.
Some of the main hardware problems that cause MCEs include:
Normal causes for MCE errors include overheating and/or incorrect hardware installation. Some specific manually-induced causes could include:
Computer software can also cause MCE errors (normally by corrupting data which programs read or write). For example, software performing read or write operations from or to non-existent memory regions can lead to confusion for the processor and/or the system bus.
As noted previously, decoding MCE errors can prove difficult. Normally the manufacturer (especially processor manufacturers) will be able to provide information about specific codes. Consult the Intel 64 and IA-32 Architectures Software Developer's Manual[2] Chapter 15 (Machine-Check Architecture), or the Microsoft KB Article on Windows Exceptions[3].