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-
-Configurable sysfs parameters for the x86-64 machine check code.
-
-Machine checks report internal hardware error conditions detected
-by the CPU. Uncorrected errors typically cause a machine check
-(often with panic), corrected ones cause a machine check log entry.
-
-Machine checks are organized in banks (normally associated with
-a hardware subsystem) and subevents in a bank. The exact meaning
-of the banks and subevent is CPU specific.
-
-mcelog knows how to decode them.
-
-When you see the "Machine check errors logged" message in the system
-log then mcelog should run to collect and decode machine check entries
-from /dev/mcelog. Normally mcelog should be run regularly from a cronjob.
-
-Each CPU has a directory in /sys/devices/system/machinecheck/machinecheckN
-(N = CPU number)
-
-The directory contains some configurable entries:
-
-Entries:
-
-bankNctl
-(N bank number)
- 64bit Hex bitmask enabling/disabling specific subevents for bank N
- When a bit in the bitmask is zero then the respective
- subevent will not be reported.
- By default all events are enabled.
- Note that BIOS maintain another mask to disable specific events
- per bank. This is not visible here
-
-The following entries appear for each CPU, but they are truly shared
-between all CPUs.
-
-check_interval
- How often to poll for corrected machine check errors, in seconds
- (Note output is hexademical). Default 5 minutes. When the poller
- finds MCEs it triggers an exponential speedup (poll more often) on
- the polling interval. When the poller stops finding MCEs, it
- triggers an exponential backoff (poll less often) on the polling
- interval. The check_interval variable is both the initial and
- maximum polling interval. 0 means no polling for corrected machine
- check errors (but some corrected errors might be still reported
- in other ways)
-
-tolerant
- Tolerance level. When a machine check exception occurs for a non
- corrected machine check the kernel can take different actions.
- Since machine check exceptions can happen any time it is sometimes
- risky for the kernel to kill a process because it defies
- normal kernel locking rules. The tolerance level configures
- how hard the kernel tries to recover even at some risk of
- deadlock. Higher tolerant values trade potentially better uptime
- with the risk of a crash or even corruption (for tolerant >= 3).
-
- 0: always panic on uncorrected errors, log corrected errors
- 1: panic or SIGBUS on uncorrected errors, log corrected errors
- 2: SIGBUS or log uncorrected errors, log corrected errors
- 3: never panic or SIGBUS, log all errors (for testing only)
-
- Default: 1
-
- Note this only makes a difference if the CPU allows recovery
- from a machine check exception. Current x86 CPUs generally do not.
-
-trigger
- Program to run when a machine check event is detected.
- This is an alternative to running mcelog regularly from cron
- and allows to detect events faster.
-monarch_timeout
- How long to wait for the other CPUs to machine check too on a
- exception. 0 to disable waiting for other CPUs.
- Unit: us
-
-TBD document entries for AMD threshold interrupt configuration
-
-For more details about the x86 machine check architecture
-see the Intel and AMD architecture manuals from their developer websites.
-
-For more details about the architecture see
-see http://one.firstfloor.org/~andi/mce.pdf