One of my servers threw another MCE this morning (Machine Check Error), and I guess it is being caused by ECC memory. I was able to capture the error codes:
CPU 0: Machine Check Exception: 0000000000000004 Bank 4: b63e200200080813 at 00000000048d7bc0 Kernel panic - not syncing: CPU context corrupt
And using mceparse, this is the explanation:
CPU 0
Status: (4) Machine Check in progress.
Restart IP invalid.
parsebank(4): b63e200200080813 @ 48d7bc0
External tag parity error
Uncorrectable ECC error
CPU state corrupt. Restart not possible
Address in addr register valid
Error enabled in control register
Error not corrected.
Bus and interconnect error
Participation: Local processor originated request
Timeout: Request did not timeout
Request: Generic error
Transaction type : Instruction
Memory/IO : Other
http://lists.us.dell.com/pipermail/linux-poweredge/2003-February/006430.html
Probably not a good idea, but I've added nomce to my boot options.
http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/install-guide/ch-bootopts.html