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| -rw-r--r-- | Documentation/ABI/removed/sysfs-mce | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/Documentation/ABI/removed/sysfs-mce b/Documentation/ABI/removed/sysfs-mce new file mode 100644 index 0000000000..ef5dd2a809 --- /dev/null +++ b/Documentation/ABI/removed/sysfs-mce @@ -0,0 +1,37 @@ +What: /sys/devices/system/machinecheck/machinecheckX/tolerant +Contact: Borislav Petkov <bp@suse.de> +Date: Dec, 2021 +Description: + Unused and obsolete after the advent of recoverable machine + checks (see last sentence below) and those are present since + 2010 (Nehalem). + + Original description: + + The entries appear for each CPU, but they are truly shared + between all CPUs. + + 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. |