that the virtual machine monitor has enabled machine check exceptions.
Unfortunately, on AMD Family 10h processors the machine check hardware
has a bug (Erratum 383) that can result in a false machine check exception
when a superpage promotion occurs. Thus, I am disabling superpage
promotion when the FreeBSD kernel is running as a guest operating system
on an AMD Family 10h processor.
Reviewed by: jhb, kib
MFC after: 3 days
0b993ee5fd