x86, mce: Add boot options for corrected errors

This patch introduces three boot options (no_cmci, dont_log_ce
and ignore_ce) to control handling for corrected errors.

The "mce=no_cmci" boot option disables the CMCI feature.

Since CMCI is a new feature so having boot controls to disable
it will be a help if the hardware is misbehaving.

The "mce=dont_log_ce" boot option disables logging for corrected
errors. All reported corrected errors will be cleared silently.
This option will be useful if you never care about corrected
errors.

The "mce=ignore_ce" boot option disables features for corrected
errors, i.e. polling timer and cmci.  All corrected events are
not cleared and kept in bank MSRs.

Usually this disablement is not recommended, however it will be
a help if there are some conflict with the BIOS or hardware
monitoring applications etc., that clears corrected events in
banks instead of OS.

[ And trivial cleanup (space -> tab) for doc is included. ]

Signed-off-by: Hidetoshi Seto <seto.hidetoshi@jp.fujitsu.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <4A30ACDF.5030408@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

1 files changed, 30 insertions, 6 deletions

diff --git a/Documentation/x86/x86_64/boot-options.txt b/Documentation/x86/x86_64/boot-options.txt
index 0ee5e3b212f3..fa2bed07d21e 100644
--- a/Documentation/x86/x86_64/boot-options.txt
+++ b/Documentation/x86/x86_64/boot-options.txt
@@ -7,12 +7,36 @@ Machine check
 
    Please see Documentation/x86/x86_64/machinecheck for sysfs runtime tunables.
 
-   mce=off disable machine check
-   mce=bootlog Enable logging of machine checks left over from booting.
-               Disabled by default on AMD because some BIOS leave bogus ones.
-               If your BIOS doesn't do that it's a good idea to enable though
-               to make sure you log even machine check events that result
-               in a reboot. On Intel systems it is enabled by default.
+   mce=off
+                Disable machine check
+   mce=no_cmci
+                Disable CMCI(Corrected Machine Check Interrupt) that
+                Intel processor supports.  Usually this disablement is
+                not recommended, but it might be handy if your hardware
+                is misbehaving.
+                Note that you'll get more problems without CMCI than with
+                due to the shared banks, i.e. you might get duplicated
+                error logs.
+   mce=dont_log_ce
+                Don't make logs for corrected errors.  All events reported
+                as corrected are silently cleared by OS.
+                This option will be useful if you have no interest in any
+                of corrected errors.
+   mce=ignore_ce
+                Disable features for corrected errors, e.g. polling timer
+                and CMCI.  All events reported as corrected are not cleared
+                by OS and remained in its error banks.
+                Usually this disablement is not recommended, however if
+                there is an agent checking/clearing corrected errors
+                (e.g. BIOS or hardware monitoring applications), conflicting
+                with OS's error handling, and you cannot deactivate the agent,
+                then this option will be a help.
+   mce=bootlog
+                Enable logging of machine checks left over from booting.
+                Disabled by default on AMD because some BIOS leave bogus ones.
+                If your BIOS doesn't do that it's a good idea to enable though
+                to make sure you log even machine check events that result
+                in a reboot. On Intel systems it is enabled by default.
    mce=nobootlog
                 Disable boot machine check logging.
    mce=tolerancelevel[,monarchtimeout] (number,number)