[PATCH 1/2] ABI: sysfs-mce: add a new ABI file

Mauro Carvalho Chehab
2021-09-28T16:02:14Z

Reduce the gap of missing ABIs for Intel servers with MCE
by adding a new ABI file.

The contents of this file comes from:
Documentation/x86/x86_64/machinecheck.rst

Cc: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
---

To mailbombing on a large number of people, only mailing lists were C/C on the cover.
See [PATCH 0/2] at: https://lore.kernel.org/all/cover.1632844726.git.mchehab+huawei@kernel.org/

Documentation/ABI/testing/sysfs-mce | 107 ++++++++++++++++++++++++++++
1 file changed, 107 insertions(+)
create mode 100644 Documentation/ABI/testing/sysfs-mce

diff --git a/Documentation/ABI/testing/sysfs-mce b/Documentation/ABI/testing/sysfs-mce
new file mode 100644
index 000000000000..d0f5095da08b
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-mce
@@ -0,0 +1,107 @@
+What: /sys/devices/system/machinecheck/machinecheckX/
+Contact: Andi Kleen <ak@linux.intel.com>
+When: Feb, 2007
+Description:
+ (X = CPU number)
+
+ 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.
+
+ 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 http://one.firstfloor.org/~andi/mce.pdf
+
+ Each CPU has its own directory.
+
+What: /sys/devices/system/machinecheck/machinecheckX/bank<Y>
+Contact: Andi Kleen <ak@linux.intel.com>
+When: Feb, 2007
+Description:
+ (Y bank number)
+
+ 64bit Hex bitmask enabling/disabling specific subevents for
+ bank Y.
+
+ 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
+
+What: /sys/devices/system/machinecheck/machinecheckX/check_interval
+Contact: Andi Kleen <ak@linux.intel.com>
+When: Feb, 2007
+Description:
+ The entries appear for each CPU, but they are truly shared
+ between all CPUs.
+
+ How often to poll for corrected machine check errors, in
+ seconds (Note output is hexadecimal). 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)
+
+What: /sys/devices/system/machinecheck/machinecheckX/tolerant
+Contact: Andi Kleen <ak@linux.intel.com>
+When: Feb, 2007
+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.
+
+What: /sys/devices/system/machinecheck/machinecheckX/trigger
+Contact: Andi Kleen <ak@linux.intel.com>
+When: Feb, 2007
+Description:
+ The entries appear for each CPU, but they are truly shared
+ between all CPUs.
+
+ 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.
+
+What: /sys/devices/system/machinecheck/machinecheckX/monarch_timeout
+Contact: Andi Kleen <ak@linux.intel.com>
+When: Feb, 2007
+Description:
+ How long to wait for the other CPUs to machine check too on a
+ exception. 0 to disable waiting for other CPUs.
+
+ Unit: us
+
--
2.31.1