[PATCH] Machine Check Architecture on amd64

Hi,

I have a simple patch for amd64 that uses the Machine Check 
Architecture/Exceptions on most recent x86 CPUs to detect memory errors:

http://people.freebsd.org/~ssouhlal/testing/mce-20070621.diff

It will report uncorrected and corrected errors (the latter, only if 
sysctl machdep.mce.log_corrected=1).
You can ask the kernel to panic if it gets an uncorrected error by 
setting machdep.mce.panic_on_uc=1.
All this can be disabled by setting the machdep.mce.enable tunable to 0. 
I'm still not sure if I want this enabled by default, as I don't have 
any Intel machines to test this on, but I have tested it on Opteron 
(both corrected and uncorrected errors).

I would appreciate it if someone would try this, especially if you have 
Intel machines with bad RAM.

Comments are welcome.

-- Suleiman