b/Documentation/watchdog/hpwdt.txt
@@ -1,64 +1,67 @@
-Last reviewed: 06/02/2009
+Last reviewed: 04/04/2016
- HP iLO2 NMI Watchdog Driver
- NMI sourcing for iLO2 based ProLiant Servers
+ HPE iLO NMI Watchdog Driver
+ NMI sourcing for iLO based ProLiant Servers
Documentation and Driver by
- Thomas Mingarelli <thomas.mingarelli@hp.com>
+ Thomas Mingarelli <thomas.mingarelli@hpe.com>
- The HP iLO2 NMI Watchdog driver is a kernel module that provides basic
+ The HPE iLO NMI Watchdog driver is a kernel module that provides basic
watchdog functionality and the added benefit of NMI sourcing. Both the
watchdog functionality and the NMI sourcing capability need to be enabled
by the user. Remember that the two modes are not dependent on one
another.
A user can have the NMI sourcing without the watchdog timer and
vice-versa.
+ All references to iLO in this document imply it also works on iLO2 and all
+ subsequent generations.
Watchdog functionality is enabled like any other common watchdog
driver. That
is, an application needs to be started that kicks off the watchdog
timer. A
basic application exists in the Documentation/watchdog/src directory
called
watchdog-test.c. Simply compile the C file and kick it off. If the system
- gets into a bad state and hangs, the HP ProLiant iLO 2 timer register will
+ gets into a bad state and hangs, the HPE ProLiant iLO timer register will
not be updated in a timely fashion and a hardware system reset (also
known as
an Automatic Server Recovery (ASR)) event will occur.
- The hpwdt driver also has four (4) module parameters. They are the
following:
+ The hpwdt driver also has three (3) module parameters. They are the
following:
- soft_margin - allows the user to set the watchdog timer value
- allow_kdump - allows the user to save off a kernel dump image after an NMI
+ soft_margin - allows the user to set the watchdog timer value.
+ Default value is 30 seconds.
+ allow_kdump - allows the user to save off a kernel dump image after an
NMI.
+ Default value is 1/ON
nowayout - basic watchdog parameter that does not allow the timer to
be restarted or an impending ASR to be escaped.
- priority - determines whether or not the hpwdt driver is first on the
- die_notify list to handle NMIs or last. The default value
- for this module parameter is 0 or LAST. If the user wants to
- enable NMI sourcing then reload the hpwdt driver with
- priority=1 (and boot with nmi_watchdog=0).
+ Default value is set when compiling the kernel. If it is set
+ to "Y", then there is no way of disabling the watchdog once
+ it has been started.
NOTE: More information about watchdog drivers in general, including
the ioctl
interface to /dev/watchdog can be found in
Documentation/watchdog/watchdog-api.txt and Documentation/IPMI.txt.
- The priority parameter was introduced due to other kernel software
that relied
- on handling NMIs (like oprofile). Keeping hpwdt's priority at 0 (or LAST)
- enables the users of NMIs for non critical events to be work as expected.
-
The NMI sourcing capability is disabled by default due to the
inability to
distinguish between "NMI Watchdog Ticks" and "HW generated NMI
events" in the
Linux kernel. What this means is that the hpwdt nmi handler code is
called
each time the NMI signal fires off. This could amount to several
thousands of
NMIs in a matter of seconds. If a user sees the Linux kernel's "dazed and
confused" message in the logs or if the system gets into a hung
state, then
- the hpwdt driver can be reloaded with the "priority" module parameter set
- (priority=1).
+ the hpwdt driver can be reloaded.
1. If the kernel has not been booted with nmi_watchdog turned off then
- edit /boot/grub/menu.lst and place the nmi_watchdog=0 at the end of the
- currently booting kernel line.
+ edit and place the nmi_watchdog=0 at the end of the currently booting
+ kernel line. Depending on your Linux distribution and platform setup:
+ For non-UEFI systems