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Vol. 3 15-43
MACHINE-CHECK ARCHITECTURE
AND PCC flag in IA32_MCi_STATUS = 1
OR RIPV flag in IA32_MCG_STATUS = 0
(* execution is not restartable *)
THEN
RESTARTABILITY = FALSE;
return RESTARTABILITY to calling procedure;
FI;
Save time-stamp counter and processor ID;
Set IA32_MCi_STATUS to all 0s;
Execute serializing instruction (i.e., CPUID);
FI;
OD;
FI;
If the processor supports the machine-check architecture, the utility reads
through the banks of error-reporting registers looking for valid register
entries. It then saves the values of the IA32_MCi_STATUS, IA32_MCi_ADDR,
IA32_MCi_MISC and IA32_MCG_STATUS registers for each bank that is
valid. The routine minimizes processing time by recording the raw data into
a system data structure or file, reducing the overhead associated with
polling. User utilities analyze the collected data in an off-line environment.
When the MCIP flag is set in the IA32_MCG_STATUS register, a machine-
check exception is in progress and the machine-check exception handler has
called the exception logging routine.
Once the logging process has been completed the exception-handling
routine must determine whether execution can be restarted, which is usually
possible when damage has not occurred (The PCC flag is clear, in the
IA32_MCi_STATUS register) and when the processor can guarantee that
execution is restartable (the RIPV flag is set in the IA32_MCG_STATUS
register). If execution cannot be restarted, the system is not recoverable
and the exception-handling routine should signal the console appropriately
before returning the error status to the Operating System kernel for subse
-
quent shutdown.
The machine-check architecture allows buffering of exceptions from a given
error-reporting bank although the Pentium 4, Intel Xeon, and P6 family
processors do not implement this feature. The error logging routine should
provide compatibility with future processors by reading each hardware
error-reporting bank's IA32_MCi_STATUS register and then writing 0s to
clear the OVER and VAL flags in this register. The error logging utility should
re-read the IA32_MCi_STATUS register for the bank ensuring that the valid
bit is clear. The processor will write the next error into the register bank and
set the VAL flags.
Additional information that should be stored by the exception-logging
routine includes the processor’s time-stamp counter value, which provides a