On Mon, Feb 23, 2015 at 01:19:46PM -0800, Andrew Morton wrote: > On Thu, 5 Feb 2015 15:40:23 -0500 Don Zickus <dzic...@redhat.com> wrote: > > > From: Ulrich Obergfell <uober...@redhat.com> > > > > 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. > > So we need a whole bunch of updates and additions to Documentation/?
Ok. > > Are all these changes back-compatible with previous kernel versions? I believe so. The motivation for some of the change was the ambiguity of the /proc/sys/kerne/watchdog variable. This patchset clears that up. So if it breaks backward compatibility, it is because it was misinterpreted from its original intention. Old definition of the proc/sys/kernel variable: watchdog == nmi_watchdog_enabled New definition: watchdog == nmi_watchdog_enabled | softlockup_enabled Cheers, Don > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
