Re: [Qemu-devel] [RFC] qmp: Return 'user_creatable' & 'hotpluggable' fields on qom-list-types

[Eric Blake]

On 05/17/2017 04:25 PM, Eduardo Habkost wrote:
> Currently there's no way for QMP clients to get a list of device types
> that are really usable with -device.  This information would be useful
> for management software and test scripts (like the device-crash-test
> script I have submitted recently).  Interestingly, the "info qdm" HMP
> command provides this information, but no QMP command does.
> 
> Add two new fields to the return value of qom-list-types:
> "user-creatable-device" and "hotpluggable-device".  Also, add extra
> arguments for filtering the list of types based on the new fields.
> 
> I'm not sure about the naming of the new command arguments.  Maybe the
> names are too long, but I believe that "user-creatable-devices-only=false"
> would have more obvious semantics than "user-creatable-devices=false"
> (the latter looks ambiguous: it could mean "return only
> non-user-creatable devices" or "return all devices").

Since this is still RFC, here's a bikeshed idea:

"just-user-creatable":false

is shorter, and still conveys whether we care about just user_creatable
devices or all devices.

> +++ b/qapi-schema.json
> @@ -3034,12 +3034,24 @@
>  #
>  # @name: the type name found in the search
>  #
> +# @user-creatable-device: If true, the type is a user-creatable device that
> +#                         can be used with the "-device" command-line option.
> +#                         Note that this does not guarantee that the device
> +#                         is going to be accepted by all machine-types.
> +#                         (since 2.10)
> +#
> +# @hotpluggable-device: If true, the type is a hotpluggable device that can
> +#                       be plugged using the "device_add" monitor command.
> +#                       Note that this does not guarantee that the device can
> +#                       be hotplugged on any machine-type. (since 2.10)

Do we need the '-device' suffix in both names?  I'm not opposed to it,
but don't know if it is adding any useful information.


>  ##
>  { 'command': 'qom-list-types',
> -  'data': { '*implements': 'str', '*abstract': 'bool' },
> +  'data': { '*implements': 'str', '*abstract': 'bool',
> +            '*user-creatable-devices-only': 'bool', 
> '*hotpluggable-devices-only': 'bool' },

Long line, try to keep it under 80 columns.

The idea looks reasonable to me.

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org

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