qemu-deprecated.texi

   1 @node Deprecated features
   2 @appendix Deprecated features
   3
   4 In general features are intended to be supported indefinitely once
   5 introduced into QEMU. In the event that a feature needs to be removed,
   6 it will be listed in this appendix. The feature will remain functional
   7 for 2 releases prior to actual removal. Deprecated features may also
   8 generate warnings on the console when QEMU starts up, or if activated
   9 via a monitor command, however, this is not a mandatory requirement.
  10
  11 Prior to the 2.10.0 release there was no official policy on how
  12 long features would be deprecated prior to their removal, nor
  13 any documented list of which features were deprecated. Thus
  14 any features deprecated prior to 2.10.0 will be treated as if
  15 they were first deprecated in the 2.10.0 release.
  16
  17 What follows is a list of all features currently marked as
  18 deprecated.
  19
  20 @section System emulator command line arguments
  21
  22 @subsection -machine enforce-config-section=on|off (since 3.1)
  23
  24 The @option{enforce-config-section} parameter is replaced by the
  25 @option{-global migration.send-configuration=@var{on|off}} option.
  26
  27 @subsection -no-kvm (since 1.3.0)
  28
  29 The ``-no-kvm'' argument is now a synonym for setting
  30 ``-machine accel=tcg''.
  31
  32 @subsection -usbdevice (since 2.10.0)
  33
  34 The ``-usbdevice DEV'' argument is now a synonym for setting
  35 the ``-device usb-DEV'' argument instead. The deprecated syntax
  36 would automatically enable USB support on the machine type.
  37 If using the new syntax, USB support must be explicitly
  38 enabled via the ``-machine usb=on'' argument.
  39
  40 @subsection -no-frame (since 2.12.0)
  41
  42 The @code{--no-frame} argument works with SDL 1.2 only. The other user
  43 interfaces never implemented this in the first place. So this will be
  44 removed together with SDL 1.2 support.
  45
  46 @subsection -clock (since 3.0.0)
  47
  48 The @code{-clock} option is ignored since QEMU version 1.7.0. There is no
  49 replacement since it is not needed anymore.
  50
  51 @subsection -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
  52
  53 The 'file' driver for drives is no longer appropriate for character or host
  54 devices and will only accept regular files (S_IFREG). The correct driver
  55 for these file types is 'host_cdrom' or 'host_device' as appropriate.
  56
  57 @subsection -net ...,name=@var{name} (since 3.1)
  58
  59 The @option{name} parameter of the @option{-net} option is a synonym
  60 for the @option{id} parameter, which should now be used instead.
  61
  62 @subsection -smp (invalid topologies) (since 3.1)
  63
  64 CPU topology properties should describe whole machine topology including
  65 possible CPUs.
  66
  67 However, historically it was possible to start QEMU with an incorrect topology
  68 where @math{@var{n} <= @var{sockets} * @var{cores} * @var{threads} < @var{maxcpus}},
  69 which could lead to an incorrect topology enumeration by the guest.
  70 Support for invalid topologies will be removed, the user must ensure
  71 topologies described with -smp include all possible cpus, i.e.
  72   @math{@var{sockets} * @var{cores} * @var{threads} = @var{maxcpus}}.
  73
  74 @section QEMU Machine Protocol (QMP) commands
  75
  76 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
  77
  78 "autoload" parameter is now ignored. All bitmaps are automatically loaded
  79 from qcow2 images.
  80
  81 @subsection query-cpus (since 2.12.0)
  82
  83 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
  84
  85 @subsection query-cpus-fast "arch" output member (since 3.0.0)
  86
  87 The ``arch'' output member of the ``query-cpus-fast'' command is
  88 replaced by the ``target'' output member.
  89
  90 @subsection cpu-add (since 4.0)
  91
  92 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
  93 documentation of ``query-hotpluggable-cpus'' for additional
  94 details.
  95
  96 @section Human Monitor Protocol (HMP) commands
  97
  98 @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
  99
 100 The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
 101 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
 102
 103 @subsection cpu-add (since 4.0)
 104
 105 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 106 documentation of ``query-hotpluggable-cpus'' for additional details.
 107
 108 @section System emulator devices
 109
 110 @subsection bluetooth (since 3.1)
 111
 112 The bluetooth subsystem is unmaintained since many years and likely bitrotten
 113 quite a bit. It will be removed without replacement unless some users speaks
 114 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
 115 their usecases.
 116
 117 @section System emulator machines
 118
 119 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
 120
 121 These machine types are very old and likely can not be used for live migration
 122 from old QEMU versions anymore. A newer machine type should be used instead.
 123
 124 @subsection prep (PowerPC) (since 3.1)
 125
 126 This machine type uses an unmaintained firmware, broken in lots of ways,
 127 and unable to start post-2004 operating systems. 40p machine type should be
 128 used instead.
 129
 130 @section Device options
 131
 132 @subsection Block device options
 133
 134 @subsubsection "backing": "" (since 2.12.0)
 135
 136 In order to prevent QEMU from automatically opening an image's backing
 137 chain, use ``"backing": null'' instead.
 138
 139 @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
 140
 141 Options for ``rbd'' should be specified according to its runtime options,
 142 like other block drivers.  Legacy parsing of keyvalue pair encoded
 143 filenames is useful to open images with the old format for backing files;
 144 These image files should be updated to use the current format.
 145
 146 Example of legacy encoding:
 147
 148 @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
 149
 150 The above, converted to the current supported format:
 151
 152 @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
 153
 154 @section Related binaries
 155
 156 @subsection qemu-nbd --partition (since 4.0.0)
 157
 158 The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
 159 can only handle MBR partitions, and has never correctly handled
 160 logical partitions beyond partition 5.  If you know the offset and
 161 length of the partition (perhaps by using @code{sfdisk} within the
 162 guest), you can achieve the effect of exporting just that subset of
 163 the disk by use of the @option{--image-opts} option with a raw
 164 blockdev using the @code{offset} and @code{size} parameters layered on
 165 top of any other existing blockdev. For example, if partition 1 is
 166 100MiB long starting at 1MiB, the old command:
 167
 168 @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
 169
 170 can be rewritten as:
 171
 172 @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
 173
 174 Alternatively, the @code{nbdkit} project provides a more powerful
 175 partition filter on top of its nbd plugin, which can be used to select
 176 an arbitrary MBR or GPT partition on top of any other full-image NBD
 177 export.  Using this to rewrite the above example results in:
 178
 179 @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
 180 @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
 181
 182 Note that if you are exposing the export via /dev/nbd0, it is easier
 183 to just export the entire image and then mount only /dev/nbd0p1 than
 184 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
 185 subset of the image.