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Diffstat (limited to 'Documentation/watchdog/hpwdt.txt')
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diff --git a/Documentation/watchdog/hpwdt.txt b/Documentation/watchdog/hpwdt.txt deleted file mode 100644 index 55df692c5595..000000000000 --- a/Documentation/watchdog/hpwdt.txt +++ /dev/null @@ -1,66 +0,0 @@ -Last reviewed: 08/20/2018 - - HPE iLO NMI Watchdog Driver - for iLO based ProLiant Servers - - The HPE iLO NMI Watchdog driver is a kernel module that provides basic - watchdog functionality and handler for the iLO "Generate NMI to System" - virtual button. - - 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 tools/testing/selftests/watchdog/ named - watchdog-test.c. Simply compile the C file and kick it off. If the system - 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 the following module parameters: - - soft_margin - allows the user to set the watchdog timer value. - Default value is 30 seconds. - timeout - an alias of soft_margin. - pretimeout - allows the user to set the watchdog pretimeout value. - This is the number of seconds before timeout when an - NMI is delivered to the system. Setting the value to - zero disables the pretimeout NMI. - Default value is 9 seconds. - nowayout - basic watchdog parameter that does not allow the timer to - be restarted or an impending ASR to be escaped. - 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. - - Due to limitations in the iLO hardware, the NMI pretimeout if enabled, - can only be set to 9 seconds. Attempts to set pretimeout to other - non-zero values will be rounded, possibly to zero. Users should verify - the pretimeout value after attempting to set pretimeout or timeout. - - Upon receipt of an NMI from the iLO, the hpwdt driver will initiate a - panic. This is to allow for a crash dump to be collected. It is incumbent - upon the user to have properly configured the system for kdump. - - The default Linux kernel behavior upon panic is to print a kernel tombstone - and loop forever. This is generally not what a watchdog user wants. - - For those wishing to learn more please see: - Documentation/kdump/kdump.txt - Documentation/admin-guide/kernel-parameters.txt (panic=) - Your Linux Distribution specific documentation. - - If the hpwdt does not receive the NMI associated with an expiring timer, - the iLO will proceed to reset the system at timeout if the timer hasn't - been updated. - --- - - The HPE iLO NMI Watchdog Driver and documentation were originally developed - by Tom Mingarelli. - |