qmp: Dumb down how we run QMP command registration

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>
7 files changed
tree: 383cdb241886b4e9309f25aa997866161d1908bf
  1. audio/
  2. backends/
  3. block/
  4. bsd-user/
  5. chardev/
  6. contrib/
  7. crypto/
  8. default-configs/
  9. disas/
  10. docs/
  11. fpu/
  12. fsdev/
  13. gdb-xml/
  14. hw/
  15. include/
  16. io/
  17. libdecnumber/
  18. linux-headers/
  19. linux-user/
  20. migration/
  21. nbd/
  22. net/
  23. pc-bios/
  24. po/
  25. qapi/
  26. qga/
  27. qobject/
  28. qom/
  29. replay/
  30. roms/
  31. scripts/
  32. slirp/
  33. stubs/
  34. target/
  35. tcg/
  36. tests/
  37. trace/
  38. ui/
  39. util/
  40. .dir-locals.el
  41. .exrc
  42. .gitignore
  43. .gitmodules
  44. .mailmap
  45. .shippable.yml
  46. .travis.yml
  47. accel.c
  48. arch_init.c
  49. atomic_template.h
  50. balloon.c
  51. block.c
  52. blockdev-nbd.c
  53. blockdev.c
  54. blockjob.c
  55. bootdevice.c
  56. bt-host.c
  57. bt-vhci.c
  58. Changelog
  59. CODING_STYLE
  60. configure
  61. COPYING
  62. COPYING.LIB
  63. cpu-exec-common.c
  64. cpu-exec.c
  65. cpus-common.c
  66. cpus.c
  67. cputlb.c
  68. device-hotplug.c
  69. device_tree.c
  70. disas.c
  71. dma-helpers.c
  72. dump.c
  73. exec.c
  74. gdbstub.c
  75. HACKING
  76. hax-stub.c
  77. hmp-commands-info.hx
  78. hmp-commands.hx
  79. hmp.c
  80. hmp.h
  81. ioport.c
  82. iothread.c
  83. kvm-all.c
  84. kvm-stub.c
  85. LICENSE
  86. MAINTAINERS
  87. Makefile
  88. Makefile.objs
  89. Makefile.target
  90. memory.c
  91. memory_ldst.inc.c
  92. memory_mapping.c
  93. module-common.c
  94. monitor.c
  95. numa.c
  96. os-posix.c
  97. os-win32.c
  98. page_cache.c
  99. qapi-schema.json
  100. qdev-monitor.c
  101. qdict-test-data.txt
  102. qemu-bridge-helper.c
  103. qemu-doc.texi
  104. qemu-ga.texi
  105. qemu-img-cmds.hx
  106. qemu-img.c
  107. qemu-img.texi
  108. qemu-io-cmds.c
  109. qemu-io.c
  110. qemu-nbd.c
  111. qemu-nbd.texi
  112. qemu-option-trace.texi
  113. qemu-options-wrapper.h
  114. qemu-options.h
  115. qemu-options.hx
  116. qemu-seccomp.c
  117. qemu-tech.texi
  118. qemu.nsi
  119. qemu.sasl
  120. qmp.c
  121. qtest.c
  122. README
  123. replication.c
  124. replication.h
  125. rules.mak
  126. softmmu_template.h
  127. spice-qemu-char.c
  128. tcg-runtime.c
  129. tci.c
  130. thunk.c
  131. tpm.c
  132. trace-events
  133. translate-all.c
  134. translate-all.h
  135. translate-common.c
  136. user-exec-stub.c
  137. user-exec.c
  138. VERSION
  139. version.rc
  140. vl.c
  141. xen-common-stub.c
  142. xen-common.c
  143. xen-hvm-stub.c
  144. xen-hvm.c
  145. xen-mapcache.c