Re: [PATCH V4 0/5] Introduce Advanced Watch Dog module

[Paolo Bonzini]

On 09/03/20 10:32, Zhang, Chen wrote:
> 4. Implementation issue.
> 
> The AWD script as an optional feature is OK for me.
> 
> And report the triggering of the watchdog via QMP events is enough for
> current usage.
> 
> But it looks have limitation to notify outside Qemu. I don't know which
> is better choice.
> 
> If the QMP events solution is better, I will fix it in next version.

Good, thanks.

Naming-wise, it's ugly that we already have a WATCHDOG event for guest
watchdog devices.  The following design however should allow setting up
multiple watchdogs

- Creating a watchdog from the command line:

-object watchdog,id=STR,timeout=NNN,chardev=CHR

and object_add/object-add can also be used for HMP and QMP.

- Reporting a watchdog timeout via QMP:

{ 'event': 'WATCHDOG_TIMEOUT',
  'data': { 'id': 'str' } }

- Protocol: the data sent on the chardev to QEMU must be

WATCHDOG=1

optionally followed by exactly one \n character.  All other data is ignored.

Paolo