Hi Guenter, Thanks a lot for the fast feedback! On Tue, Apr 13, 2021 at 09:15:35AM -0700, Guenter Roeck wrote: > On 4/13/21 8:45 AM, Stefan Eichenberger wrote: > > Add a governor which calls a notifier call chain. This allows the > > registration of custom functions to the watchdog pretimeout. This is > > useful when writing out-of-tree kernel modules and it is more similar to > > the register_reboot_notifier or register_oom_notifier API. > > > > Signed-off-by: Stefan Eichenberger <eichest@xxxxxxxxx> > > It seems questionable to implement such a notification as governor. > A governor is configurable, and letting userspace override notifications > seems very odd and unusual. Please provide a use case. What I would like to do is to have an out-of-tree module which will write a pattern into a reserved memory region when a watchdog occurs. After a reboot the module then read this reserved memory region and can differentiate between different reset reasons. Here the example kernel module: https://github.com/embear-engineering/sample-kernel-modules/blob/use-watchdog-register/reset-reason/reset-reason.c Registering to the watchdog happens on line 180. I think I could just implement a governor in the module but it is not really flexible because then I would have to compile the kernel with e.g. the noop governor and then switch to my governor after the module loaded. Then I thought why not using a notifier chain similar to reboot, panic, or oom. Regards, Stefan
