Intel 253668-032US User Manual

15-42 Vol. 3

MACHINE-CHECK ARCHITECTURE

When machine-check exceptions are enabled for the Pentium processor

(MCE flag is set in control register CR4), the machine-check exception

handler uses the RDMSR instruction to read the error type from the

P5_MC_TYPE register and the machine check address from the

P5_MC_ADDR register. The handler then normally reports these register

values to the system console before aborting execution (see Example 15-2).

15.10.3 Logging Correctable Machine-Check Errors

The error handling routine for servicing the machine-check exceptions is

responsible for logging uncorrected errors.
If a machine-check error is correctable, the processor does not generate a

machine-check exception for it. To detect correctable machine-check errors,

a utility program must be written that reads each of the machine-check

error-reporting register banks and logs the results in an accounting file or

data structure. This utility can be implemented in either of the following

ways.

•

A system daemon that polls the register banks on an infrequent basis, such as
hourly or daily.

•

A user-initiated application that polls the register banks and records the
exceptions. Here, the actual polling service is provided by an operating-system
driver or through the system call interface.

•

An interrupt service routine servicing CMCI can read the MC banks and log the
error.

Example 15-3 gives pseudocode for an error logging utility.

Example 15-3. Machine-Check Error Logging Pseudocode

Assume that execution is restartable;

IF the processor supports MCA

THEN

FOR each bank of machine-check registers

READ IA32_MCi_STATUS;

IF VAL flag in IA32

MCi_STATUS = 1

THEN

IF ADDRV flag in IA32_MCi_STATUS = 1

THEN READ IA32_MCi_ADDR;

FI;
IF MISCV flag in IA32_MCi_STATUS = 1

THEN READ IA32_MCi_MISC;

FI;
IF MCIP flag in IA32_MCG_STATUS = 1

(* Machine-check exception is in progress *)