Re: [Xen-users] Watchdog and live migration

[Wouter de Geus <benv-xensource.com@xxxxxxxxxxxxx>]

* Ian Campbell <Ian.Campbell@xxxxxxxxxx> [2012-03-16 10:55:34 +0000]:

> > In the domU a /dev/watchdog exists, but I never touch it myself.
> 
> Does your distro start a watchdogd for you?
> 
> Even if it did then it should obviously continue to poke the watchdog
> even after a migration, but it might provide some hints.

Nope, it doesn't.
As an experiemtn I tried sending a 'V' to /dev/watchdog just after 
migration, which seems to be the magic byte to stop the watchdog 
according to the linux kernel docs.

(according to Documentation/watchdog/watchdog-api.txt) - 
"If a driver supports "Magic Close", the driver will not disable the
watchdog unless a specific magic character 'V' has been sent to
/dev/watchdog just before closing the file."

Surprisingly, the domU seemed to stay alive after doing this.
So it would appear that somehow the watchdog is triggered after migration.
No idea why though.

Wouter.

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