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authorUlrich Obergfell <uobergfe@redhat.com>2015-04-15 01:44:13 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-15 02:48:59 +0300
commit195daf665a6299de98a4da3843fed2dd9de19d3a (patch)
tree3f7b786d4dfafa6a4d4090e529f7858f60112c75 /Documentation/kernel-parameters.txt
parentbcfba4f4bf3c9c7c72b459d52a9e826dfd72855e (diff)
downloadlinux-195daf665a6299de98a4da3843fed2dd9de19d3a.tar.xz
watchdog: enable the new user interface of the watchdog mechanism
With the current user interface of the watchdog mechanism it is only possible to disable or enable both lockup detectors at the same time. This series introduces new kernel parameters and changes the semantics of some existing kernel parameters, so that the hard lockup detector and the soft lockup detector can be disabled or enabled individually. With this series applied, the user interface is as follows. - parameters in /proc/sys/kernel . soft_watchdog This is a new parameter to control and examine the run state of the soft lockup detector. . nmi_watchdog The semantics of this parameter have changed. It can now be used to control and examine the run state of the hard lockup detector. . watchdog This parameter is still available to control the run state of both lockup detectors at the same time. If this parameter is examined, it shows the logical OR of soft_watchdog and nmi_watchdog. . watchdog_thresh The semantics of this parameter are not affected by the patch. - kernel command line parameters . nosoftlockup The semantics of this parameter have changed. It can now be used to disable the soft lockup detector at boot time. . nmi_watchdog=0 or nmi_watchdog=1 Disable or enable the hard lockup detector at boot time. The patch introduces '=1' as a new option. . nowatchdog The semantics of this parameter are not affected by the patch. It is still available to disable both lockup detectors at boot time. Also, remove the proc_dowatchdog() function which is no longer needed. [dzickus@redhat.com: wrote changelog] [dzickus@redhat.com: update documentation for kernel params and sysctl] Signed-off-by: Ulrich Obergfell <uobergfe@redhat.com> Signed-off-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'Documentation/kernel-parameters.txt')
-rw-r--r--Documentation/kernel-parameters.txt6
1 files changed, 4 insertions, 2 deletions
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 01aa47d3b6ab..71eecb263250 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2236,8 +2236,9 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nmi_watchdog= [KNL,BUGS=X86] Debugging features for SMP kernels
Format: [panic,][nopanic,][num]
- Valid num: 0
+ Valid num: 0 or 1
0 - turn nmi_watchdog off
+ 1 - turn nmi_watchdog on
When panic is specified, panic when an NMI watchdog
timeout occurs (or 'nopanic' to override the opposite
default).
@@ -2464,7 +2465,8 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
nousb [USB] Disable the USB subsystem
- nowatchdog [KNL] Disable the lockup detector (NMI watchdog).
+ nowatchdog [KNL] Disable both lockup detectors, i.e.
+ soft-lockup and NMI watchdog (hard-lockup).
nowb [ARM]