Re: [Qemu-devel] [RFC 1/1] Execute arbitrary QMP commands from command line

[Amit Shah]

On (Fri) 30 Jan 2015 [10:50:26], Paolo Bonzini wrote:
> 
> 
> On 30/01/2015 10:38, Dr. David Alan Gilbert wrote:
> > * Eric Blake (address@hidden) wrote:
> >> On 01/29/2015 01:21 PM, Dr. David Alan Gilbert wrote:
> >>> * Eric Blake (address@hidden) wrote:
> >>>> On 01/29/2015 09:28 AM, Dr. David Alan Gilbert wrote:
> >>>>>
> >>>>> So what would the .args_type look like in qmp-commands.hx; something 
> >>>>> like this?
> >>>>>
> >>>>>   .args-type = "type:s,port:-i,host:-s,command:-s"
> >>>>
> >>>> No, it would be more like the blockdev-add interface, where one command
> >>>> accepts a dictionary object containing a union of valid values, where
> >>>> the set of valid values is determined by the discriminator field.
> >>>> .args_type = "options:q".
> >>>
> >>> What causes the parser to generate a 'BlockdevOptions' as opposed to any
> >>> standard options type for the parameter of qmp_blockdev_add?
> >>
> >> Kevin Wolf has the most experience here, as he was the one that figured
> >> out how to correlate command line and QMP as part of adding blockdev-add.
> > 
> > OK, this is getting more complicated than I'd expected; how about a simpler
> > suggestion.
> > 
> > The current suggestion is:
> >    Modify  -incoming to take   'pause' as an argument
> 
> -S is just the same.

(just putting this in w/o actually checking..)

Does -S and -incoming differ in the 'do not read disks' case?  I
recall we had to add consistency checks so that the destination qemu
didn't inadvertently read disk metadata on shared storage before
migration had finished (so that an in-progress disk size / partition
size update on the src wasn't getting reflected on the dest, causing
migration failures during guest installation).

> >    Add migrate-incoming command that takes parsed URI
> > 
> > New suggestion:
> >    Modify -incoming to take a pause: prefix (e.g. -incoming 
> > pause:tcp:host:port )
> >    Add migrate-incoming-start command (takes no arguments).
> 
> Another suggestion:
> 
> Add incoming argument to the existing URI-based command migrate.
> 
> Later on, if ever, add start-migration command that takes structured
> options, make HMP and QMP migrate wrappers for start-migration.

FWIW I've only followed a part of the thread so far, catching up on
the rest, but the pause option looks good to me.

                Amit