38 lines
1.4 KiB
Plaintext
38 lines
1.4 KiB
Plaintext
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What: /sys/devices/system/machinecheck/machinecheckX/tolerant
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Contact: Borislav Petkov <bp@suse.de>
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Date: Dec, 2021
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Description:
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Unused and obsolete after the advent of recoverable machine
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checks (see last sentence below) and those are present since
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2010 (Nehalem).
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Original description:
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The entries appear for each CPU, but they are truly shared
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between all CPUs.
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Tolerance level. When a machine check exception occurs for a
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non corrected machine check the kernel can take different
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actions.
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Since machine check exceptions can happen any time it is
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sometimes risky for the kernel to kill a process because it
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defies normal kernel locking rules. The tolerance level
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configures how hard the kernel tries to recover even at some
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risk of deadlock. Higher tolerant values trade potentially
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better uptime with the risk of a crash or even corruption
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(for tolerant >= 3).
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== ===========================================================
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0 always panic on uncorrected errors, log corrected errors
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1 panic or SIGBUS on uncorrected errors, log corrected errors
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2 SIGBUS or log uncorrected errors, log corrected errors
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3 never panic or SIGBUS, log all errors (for testing only)
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== ===========================================================
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Default: 1
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Note this only makes a difference if the CPU allows recovery
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from a machine check exception. Current x86 CPUs generally
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do not.
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