can the hardware watchdog reboot a hung kernel?

[Eugene Grosbein]

15.11.2019 1:19, Ian Lepore wrote:

> One thing to be careful of here is multicore systems.  If you have a
> critical app running on a multicore system, that app can hang (maybe it
> tries to read from a device that has malfunctioned and essentially gets
> hung forever in a device driver that doesn't implement timeouts very
> well or something).  In that case, only one core is hung, so watchdogd
> will be able to keep petting the dog to prevent a reboot, but since
> your app is hung on a different core, you aren't really getting the
> protection you need.
> 
> The fix for that is to either turn you app into watchdogd (have it make
> the periodic ioctl() calls to pet the dog), or use the '-e cmd' option
> with watchdogd, and make 'cmd' be a script that somehow verifies that
> your critical application is still running properly.

I have not tried it myself, but there may be easier way
if the app is single-process and single-threaded: use cpuset(1) to bind
both of the app and watchdogd to same core.