[Qemu-devel] how to setup a watchdog?

[Qemu-devel] how to setup a watchdog?

[lejeczek]

apologies I bother devel, but..
I tried to get help on libvirt mailing list but not luck, 
then qemu, still nothing
I hope maybe somebody here?

I'm trying Qemu's watchdog.
My understanding was that hardware (here qemu's watchdog) 
would take
action, eg. cold reboot the system if there is no ping from 
the OS watchdog, so I
thought stopping watchdog service in VM should be a quick 
test, right?

I have this in the guest:

     <watchdog model='i6300esb' action='reset'>
       <address type='pci' domain='0x0000' bus='0x00' 
slot='0x08' function='0x0'/>
     </watchdog>

and I see /dev/watchdog in my guest. Yet nothing happens, 
guest(linux) runs uninterrupted.
I must be missing something, an expert said it's config 
problem, is it really is?

many thanks

Re: [Qemu-devel] how to setup a watchdog?

[Philipp Hahn]

Hi,

Am 18.01.2016 um 12:43 schrieb lejeczek:
> I'm trying Qemu's watchdog.
> My understanding was that hardware (here qemu's watchdog) would take
> action, eg. cold reboot the system if there is no ping from the OS
> watchdog, so I
> thought stopping watchdog service in VM should be a quick test, right?
> 
> I have this in the guest:
> 
>     <watchdog model='i6300esb' action='reset'>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x08' function='0x0'/>
>     </watchdog>
> 
> and I see /dev/watchdog in my guest. Yet nothing happens, guest(linux)
> runs uninterrupted.
> I must be missing something, an expert said it's config problem, is it
> really is?

Probably reading linux/Documentation/watchdog/watchdog-api.txt should
give you some extra hints.

AFAIK you need to open that device file at least once, either with the
sample program included in the Linux source tree, or by another program
like (Debian) watchdog or systemd (man 5 systemd-system.conf ->
RuntimeWatchdogSec)

  cat /dev/watchdog # will print an error about the read(), but the
important thing (opening the file) has been done
  dmesg | grep watchdog # will print "i6300esb: Unexpected close, not
stopping watchdog!" to show you that the watchdog is still running and
will trigger the reboot, as it has gone through the shutdown protocol,
which can be used to disable the watchdog again

After ~1m my test VM rebooted.

Philipp

Re: [Qemu-devel] how to setup a watchdog?

[Richard W.M. Jones]

On Mon, Jan 18, 2016 at 11:43:02AM +0000, lejeczek wrote:
> apologies I bother devel, but..
> I tried to get help on libvirt mailing list but not luck, then qemu,
> still nothing
> I hope maybe somebody here?
> 
> I'm trying Qemu's watchdog.
> My understanding was that hardware (here qemu's watchdog) would take
> action, eg. cold reboot the system if there is no ping from the OS
> watchdog, so I
> thought stopping watchdog service in VM should be a quick test,
> right?
> 
> I have this in the guest:
> 
>     <watchdog model='i6300esb' action='reset'>
>       <address type='pci' domain='0x0000' bus='0x00' slot='0x08'
> function='0x0'/>
>     </watchdog>
> 
> and I see /dev/watchdog in my guest. Yet nothing happens,
> guest(linux) runs uninterrupted.
> I must be missing something, an expert said it's config problem, is
> it really is?

Sorry for the late response.

If your guest is Linux, you must also run the watchdog daemon in the
guest.  The watchdog device's timer isn't primed until it is opened
and set up by the watchdog daemon.

There is basically no watchdog framework or support in Windows, so
you'll have to write the software and driver yourself.

Rich.

-- 
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