The way we get QMP commands registered is high tech:
* qapi-commands.py generates qmp_init_marshal() that does the actual work
* it also generates the magic to register it as a MODULE_INIT_QAPI
function, so it runs when someone calls
module_call_init(MODULE_INIT_QAPI)
* main() calls module_call_init()
QEMU needs to register a few non-qapified commands. Same high tech
works: monitor.c has its own qmp_init_marshal() along with the magic
to make it run in module_call_init(MODULE_INIT_QAPI).
QEMU also needs to unregister commands that are not wanted in this
build's configuration (commit 5032a16). Simple enough:
qmp_unregister_commands_hack(). The difficulty is to make it run
after the generated qmp_init_marshal(). We can't simply run it in
monitor.c's qmp_init_marshal(), because the order in which the
registered functions run is indeterminate. So qmp_init_marshal()
registers qmp_unregister_commands_hack() separately. Since
registering *appends* to the list of registered functions, this will
make it run after all the functions that have been registered already.
I suspect it takes a long and expensive computer science education to
not find this silly.
Dumb it down as follows:
* Drop MODULE_INIT_QAPI entirely
* Give the generated qmp_init_marshal() external linkage.
* Call it instead of module_call_init(MODULE_INIT_QAPI)
* Except in QEMU proper, call new monitor_init_qmp_commands() that in
turn calls the generated qmp_init_marshal(), registers the
additional commands and unregisters the unwanted ones.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1488544368-30622-5-git-send-email-armbru@redhat.com>
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