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| author | Borislav Petkov <bp@suse.de> | 2021-12-20 23:43:28 +0300 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-02-23 13:09:25 +0300 |
| commit | 7f1b8e0d6360178e3527d4f14e6921c254a86035 (patch) | |
| tree | 21fd1faf6a1cbe36343dc8330da52c750bee7a33 /Documentation/ABI/removed | |
| parent | 8ca97812c3c830573f965a07bbd84223e8c5f5bd (diff) | |
| download | linux-7f1b8e0d6360178e3527d4f14e6921c254a86035.tar.xz | |
x86/mce: Remove the tolerance level control
This is pretty much unused and not really useful. What is more, all
relevant MCA hardware has recoverable machine checks support so there's
no real need to tweak MCA tolerance levels in order to *maybe* extend
machine lifetime.
So rip it out.
Signed-off-by: Borislav Petkov <bp@suse.de>
Link: https://lore.kernel.org/r/YcDq8PxvKtTENl/e@zn.tnic
Diffstat (limited to 'Documentation/ABI/removed')
| -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 000000000000..ef5dd2a80918 --- /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. |