[{"id":3674495,"web_url":"http://patchwork.ozlabs.org/comment/3674495/","msgid":"<20260407-erhitzen-anlaufen-ffbbd453251b@brauner>","list_archive_url":null,"date":"2026-04-07T20:59:05","subject":"Re: [PATCH v3 3/5] qapi: add monitor-add, monitor-remove,\n query-monitors commands","submitter":{"id":82326,"url":"http://patchwork.ozlabs.org/api/people/82326/","name":"Christian Brauner","email":"brauner@kernel.org"},"content":"On Tue, Apr 07, 2026 at 11:45:53AM +0100, Daniel P. Berrangé wrote:\n> On Tue, Apr 07, 2026 at 09:32:47AM +0200, Christian Brauner wrote:\n> > Add QMP commands for dynamic monitor lifecycle management:\n> > \n> > - monitor-add: Create a QMP monitor on an existing chardev at runtime.\n> > The chardev must exist and not already have a frontend attached\n> > (enforced by qemu_chr_fe_init()). The new monitor starts in\n> > capability negotiation mode.\n> > \n> > - monitor-remove: Remove a dynamically-added monitor. CLI-created\n> > monitors cannot be removed. The removal sequence is:\n> \n> Why should we block removal of statically created monitors ? Our\n> normal approach is that the creation of objects via the command\n> line & QMP be indistinguishable.\n\nSounds fine to me.\n\n> \n> \n> > diff --git a/qapi/control.json b/qapi/control.json\n> > index 9a5302193d..fd58b57c31 100644\n> > --- a/qapi/control.json\n> > +++ b/qapi/control.json\n> > @@ -211,3 +211,107 @@\n> > '*pretty': 'bool',\n> > 'chardev': 'str'\n> > } }\n> > +\n> > +##\n> > +# @monitor-add:\n> > +#\n> > +# Add a QMP monitor on an existing character device backend.\n> > +#\n> > +# The chardev must already exist (created via chardev-add or CLI).\n> > +# The monitor begins in capability negotiation mode -- the first\n> > +# client to connect receives the QMP greeting.\n> > +#\n> > +# @id: Monitor identifier, must be unique among monitors\n> > +#\n> > +# @chardev: Name of the character device backend to attach to\n> > +#\n> > +# @pretty: Enable pretty-printing of QMP responses (default: false)\n> > +#\n> > +# Errors:\n> > +# - GenericError if @id is already in use\n> > +# - GenericError if @chardev does not exist\n> > +#\n> > +# Since: 11.0\n> \n> We're just about to release 11.0, so 11.1 is the earliest\n> opportunity to merge anything now.\n\nI mostly copy-pasted this together. I honestly had no idea what the\ncurrent release cycle is.\n\n> \n> > +#\n> > +# .. qmp-example::\n> > +#\n> > +# -> { \"execute\": \"monitor-add\",\n> > +# \"arguments\": { \"id\": \"extra-qmp\",\n> > +# \"chardev\": \"qmp-extra\" } }\n> > +# <- { \"return\": {} }\n> > +##\n> > +{ 'command': 'monitor-add',\n> > + 'data': { 'id': 'str',\n> > + 'chardev': 'str',\n> > + '*pretty': 'bool' } }\n> > +\n> > +##\n> > +# @monitor-remove:\n> > +#\n> > +# Remove a dynamically added QMP monitor.\n> > +#\n> > +# The monitor must have been created via monitor-add. Monitors\n> > +# created via CLI options (-mon, -qmp) cannot be removed. The\n> > +# underlying chardev is NOT removed -- use chardev-remove separately\n> > +# if desired.\n> > +#\n> > +# If a client is currently connected, the connection is dropped.\n> > +#\n> > +# @id: Monitor identifier as passed to monitor-add\n> > +#\n> > +# Errors:\n> > +# - GenericError if @id does not exist\n> > +# - GenericError if the monitor was not dynamically added\n> \n> I don't think we need to include \"GenericError\" in the description.\n> We've abandoned the idea of error classes in general, so everything\n> is GenericError except for a bit of historical cruft.\n\nOk.\n\n> \n> > +#\n> > +# Since: 11.0\n> > +#\n> > +# .. qmp-example::\n> > +#\n> > +# -> { \"execute\": \"monitor-remove\",\n> > +# \"arguments\": { \"id\": \"extra-qmp\" } }\n> > +# <- { \"return\": {} }\n> > +##\n> > +{ 'command': 'monitor-remove',\n> > + 'data': { 'id': 'str' } }\n> > +\n> > +##\n> > +# @MonitorInfo:\n> > +#\n> > +# Information about a QMP/HMP monitor.\n> > +#\n> > +# @id: Monitor identifier (absent for CLI-created monitors without\n> > +# an explicit id)\n> \n> We can't make 'id' mandatory for the existing arg without breaking\n> compat, but IMHO we should allocate an auto-generated 'id' if the\n> user omits it.\n\nOk.","headers":{"Return-Path":"","X-Original-To":"incoming@patchwork.ozlabs.org","Delivered-To":"patchwork-incoming@legolas.ozlabs.org","Authentication-Results":["legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256\n header.s=k20201202 header.b=Ig7dF6hc;\n\tdkim-atps=neutral","legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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