Re: [Qemu-devel] QMP: RFC: I/O error info & query-stop-reason

[Daniel P. Berrange]

On Fri, Jun 03, 2011 at 08:26:56AM -0500, Anthony Liguori wrote:
> On 06/03/2011 07:57 AM, Daniel P. Berrange wrote:
> >On Fri, Jun 03, 2011 at 07:43:24AM -0500, Anthony Liguori wrote:
> >>On 06/03/2011 04:26 AM, Daniel P. Berrange wrote:
> >>errors stop a guest) instead of trying to model an internal QEMU
> >>concept (vm_stop()).
> >>
> >>If you have other user visible concepts that you want to know about,
> >>please share the use-cases and we can think about how to model it
> >>such that it's not exposing internal QEMU details.
> >
> >None of the requested info is exposing internal QEMU impl details
> >with one exception. The reasons are either administrative commands,
> >host OS failures, guest OS failures, or the exception, KVM internal
> >emulation failure.
> >
> >The core problem is that an app connects to QEMU, finds it is paused,
> >and wants to decide what action to take. If the guest is paused due
> >to a previous admin 'stop' command,
> 
> Let's be very clear here.  QEMU does not provide a way to figure out
> what the previous QMP user did.  That is not a use case we support
> today and it's not one we can support by just adding a reason to
> stop.  It's far more complicated than just that.
> 
> >it will allow resuming. If it is
> >paused due to guest OS poweroff,
> 
> This is legitimate but only occurs if you use -no-shutdown.  So
> having a query-state have a "powered-off" flag would be a Good
> Thing.
> 
> >it might decide to issue a 'system_reset'
> >command and then 'resume'. If it is paused due to watchdog,
> 
> I think what we're getting at is the need for an enumeration.  So
> let's introduce one.  Here's what I propose:
> 
> SQMP
> query-status
> ------------
> 
> Return a json-object with the following information:
> 
> - "running": true if the VM is running, or false if it is paused (json-bool)
> - "singlestep": true if the VM is in single step mode,
>                 false otherwise (json-bool)
> - "status": one of the following values (json-string) (optional)
>       "prelaunch" - QEMU was started with -S and guest has not started
>       "running" - guest is actively running
>       "singlestep" - guest is running in single step mode
>       "paused" - guest has been paused via the 'stop' command
>       "postmigrate" - guest is paused following a successful 'migrate'
>       "shutdown" - guest is shut down (and -no-shutdown is in use)
>       "io-error" - the last IOP has failed and the device is
> configured to pause on I/O errors
>       "watchdog-error" - the watchdog action is configured to pause
> and has been triggered

Perhaps I didn't communicate well, but this pretty much matches
what I was trying to ask for in my previous message, so gets
my vote!


Daniel
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