Re: [Qemu-devel] [PATCH] vl: add -libvirt-caps option for libvirt to stop parsing help output

["Daniel P. Berrange" <berrange@redhat.com>]

On Fri, Jul 27, 2012 at 01:23:03PM +0200, Markus Armbruster wrote:
> 
> Assuming version X (according to query-version) supports no less than
> upstream version X sounds fair.
> 
> If a command line option has a corresponding QMP command, probing QMP
> for the feature suffices.  For instance, query-devices gives you devices
> for -device.
> 
> I'm afraid there could still be an occasional need for probing the
> command line.  A simple, machine-readable command line self-description
> could satisfy it.  Something like:
> 
> - query-cmdline-options: JSON representation of qemu_options[], with
>   unnecessary detail elided.  Basically option name and whether it takes
>   an argument.
> 
> For options with a QemuOpts argument, we may want to add argument
> self-description.  Basically its QemuOptsList, with unnecessary detail
> elided.  Non-QemuOpts arguments don't get that.  New structured option
> arguments should use QemuOpts anyway.
> 
> Some users might prefer to get this via a command line option rather
> than a QMP command.  They should ask for it.

In my original proposal from 2 years back, I actually exposed a number
of QMP query-XXX commands via a -capabilities XXXX command line args.
On revisiting it though, I think that since we'll want to ask for
info on many different aspects, it is easier just to use QMP directly
rather than string together various command line args upfront, or
invoke QEMU multiple times.

Daniel
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