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  1. @node Deprecated features
  2. @appendix Deprecated features
  3. In general features are intended to be supported indefinitely once
  4. introduced into QEMU. In the event that a feature needs to be removed,
  5. it will be listed in this appendix. The feature will remain functional
  6. for 2 releases prior to actual removal. Deprecated features may also
  7. generate warnings on the console when QEMU starts up, or if activated
  8. via a monitor command, however, this is not a mandatory requirement.
  9. Prior to the 2.10.0 release there was no official policy on how
  10. long features would be deprecated prior to their removal, nor
  11. any documented list of which features were deprecated. Thus
  12. any features deprecated prior to 2.10.0 will be treated as if
  13. they were first deprecated in the 2.10.0 release.
  14. What follows is a list of all features currently marked as
  15. deprecated.
  16. @section System emulator command line arguments
  17. @subsection -machine enforce-config-section=on|off (since 3.1)
  18. The @option{enforce-config-section} parameter is replaced by the
  19. @option{-global migration.send-configuration=@var{on|off}} option.
  20. @subsection -no-kvm (since 1.3.0)
  21. The ``-no-kvm'' argument is now a synonym for setting
  22. ``-machine accel=tcg''.
  23. @subsection -usbdevice (since 2.10.0)
  24. The ``-usbdevice DEV'' argument is now a synonym for setting
  25. the ``-device usb-DEV'' argument instead. The deprecated syntax
  26. would automatically enable USB support on the machine type.
  27. If using the new syntax, USB support must be explicitly
  28. enabled via the ``-machine usb=on'' argument.
  29. @subsection -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
  30. The 'file' driver for drives is no longer appropriate for character or host
  31. devices and will only accept regular files (S_IFREG). The correct driver
  32. for these file types is 'host_cdrom' or 'host_device' as appropriate.
  33. @subsection -net ...,name=@var{name} (since 3.1)
  34. The @option{name} parameter of the @option{-net} option is a synonym
  35. for the @option{id} parameter, which should now be used instead.
  36. @subsection -smp (invalid topologies) (since 3.1)
  37. CPU topology properties should describe whole machine topology including
  38. possible CPUs.
  39. However, historically it was possible to start QEMU with an incorrect topology
  40. where @math{@var{n} <= @var{sockets} * @var{cores} * @var{threads} < @var{maxcpus}},
  41. which could lead to an incorrect topology enumeration by the guest.
  42. Support for invalid topologies will be removed, the user must ensure
  43. topologies described with -smp include all possible cpus, i.e.
  44. @math{@var{sockets} * @var{cores} * @var{threads} = @var{maxcpus}}.
  45. @section QEMU Machine Protocol (QMP) commands
  46. @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
  47. "autoload" parameter is now ignored. All bitmaps are automatically loaded
  48. from qcow2 images.
  49. @subsection query-cpus (since 2.12.0)
  50. The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
  51. @subsection query-cpus-fast "arch" output member (since 3.0.0)
  52. The ``arch'' output member of the ``query-cpus-fast'' command is
  53. replaced by the ``target'' output member.
  54. @subsection cpu-add (since 4.0)
  55. Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See
  56. documentation of ``query-hotpluggable-cpus'' for additional
  57. details.
  58. @subsection query-events (since 4.0)
  59. The ``query-events'' command has been superseded by the more powerful
  60. and accurate ``query-qmp-schema'' command.
  61. @section Human Monitor Protocol (HMP) commands
  62. @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
  63. The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
  64. 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
  65. @subsection cpu-add (since 4.0)
  66. Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See
  67. documentation of ``query-hotpluggable-cpus'' for additional details.
  68. @section System emulator devices
  69. @subsection bluetooth (since 3.1)
  70. The bluetooth subsystem is unmaintained since many years and likely bitrotten
  71. quite a bit. It will be removed without replacement unless some users speaks
  72. up at the @email{} mailing list with information about
  73. their usecases.
  74. @section System emulator machines
  75. @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
  76. These machine types are very old and likely can not be used for live migration
  77. from old QEMU versions anymore. A newer machine type should be used instead.
  78. @subsection prep (PowerPC) (since 3.1)
  79. This machine type uses an unmaintained firmware, broken in lots of ways,
  80. and unable to start post-2004 operating systems. 40p machine type should be
  81. used instead.
  82. @section Device options
  83. @subsection Block device options
  84. @subsubsection "backing": "" (since 2.12.0)
  85. In order to prevent QEMU from automatically opening an image's backing
  86. chain, use ``"backing": null'' instead.
  87. @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
  88. Options for ``rbd'' should be specified according to its runtime options,
  89. like other block drivers. Legacy parsing of keyvalue pair encoded
  90. filenames is useful to open images with the old format for backing files;
  91. These image files should be updated to use the current format.
  92. Example of legacy encoding:
  93. @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
  94. The above, converted to the current supported format:
  95. @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
  96. @section Related binaries
  97. @subsection qemu-nbd --partition (since 4.0.0)
  98. The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
  99. can only handle MBR partitions, and has never correctly handled
  100. logical partitions beyond partition 5. If you know the offset and
  101. length of the partition (perhaps by using @code{sfdisk} within the
  102. guest), you can achieve the effect of exporting just that subset of
  103. the disk by use of the @option{--image-opts} option with a raw
  104. blockdev using the @code{offset} and @code{size} parameters layered on
  105. top of any other existing blockdev. For example, if partition 1 is
  106. 100MiB long starting at 1MiB, the old command:
  107. @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
  108. can be rewritten as:
  109. @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
  110. Alternatively, the @code{nbdkit} project provides a more powerful
  111. partition filter on top of its nbd plugin, which can be used to select
  112. an arbitrary MBR or GPT partition on top of any other full-image NBD
  113. export. Using this to rewrite the above example results in:
  114. @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
  115. @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
  116. Note that if you are exposing the export via /dev/nbd0, it is easier
  117. to just export the entire image and then mount only /dev/nbd0p1 than
  118. it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
  119. subset of the image.