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 -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
  41
  42 The 'file' driver for drives is no longer appropriate for character or host
  43 devices and will only accept regular files (S_IFREG). The correct driver
  44 for these file types is 'host_cdrom' or 'host_device' as appropriate.
  45
  46 @subsection -net ...,name=@var{name} (since 3.1)
  47
  48 The @option{name} parameter of the @option{-net} option is a synonym
  49 for the @option{id} parameter, which should now be used instead.
  50
  51 @subsection -smp (invalid topologies) (since 3.1)
  52
  53 CPU topology properties should describe whole machine topology including
  54 possible CPUs.
  55
  56 However, historically it was possible to start QEMU with an incorrect topology
  57 where @math{@var{n} <= @var{sockets} * @var{cores} * @var{threads} < @var{maxcpus}},
  58 which could lead to an incorrect topology enumeration by the guest.
  59 Support for invalid topologies will be removed, the user must ensure
  60 topologies described with -smp include all possible cpus, i.e.
  61   @math{@var{sockets} * @var{cores} * @var{threads} = @var{maxcpus}}.
  62
  63 @subsection -vnc acl (since 4.0.0)
  64
  65 The @code{acl} option to the @code{-vnc} argument has been replaced
  66 by the @code{tls-authz} and @code{sasl-authz} options.
  67
  68 @subsection QEMU_AUDIO_ environment variables and -audio-help (since 4.0)
  69
  70 The ``-audiodev'' argument is now the preferred way to specify audio
  71 backend settings instead of environment variables.  To ease migration to
  72 the new format, the ``-audiodev-help'' option can be used to convert
  73 the current values of the environment variables to ``-audiodev'' options.
  74
  75 @section QEMU Machine Protocol (QMP) commands
  76
  77 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
  78
  79 "autoload" parameter is now ignored. All bitmaps are automatically loaded
  80 from qcow2 images.
  81
  82 @subsection query-block result field dirty-bitmaps[i].status (since 4.0)
  83
  84 The ``status'' field of the ``BlockDirtyInfo'' structure, returned by
  85 the query-block command is deprecated. Two new boolean fields,
  86 ``recording'' and ``busy'' effectively replace it.
  87
  88 @subsection query-cpus (since 2.12.0)
  89
  90 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
  91
  92 @subsection query-cpus-fast "arch" output member (since 3.0.0)
  93
  94 The ``arch'' output member of the ``query-cpus-fast'' command is
  95 replaced by the ``target'' output member.
  96
  97 @subsection cpu-add (since 4.0)
  98
  99 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 100 documentation of ``query-hotpluggable-cpus'' for additional
 101 details.
 102
 103 @subsection query-events (since 4.0)
 104
 105 The ``query-events'' command has been superseded by the more powerful
 106 and accurate ``query-qmp-schema'' command.
 107
 108 @section Human Monitor Protocol (HMP) commands
 109
 110 @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
 111
 112 The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
 113 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
 114
 115 @subsection cpu-add (since 4.0)
 116
 117 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 118 documentation of ``query-hotpluggable-cpus'' for additional details.
 119
 120 @subsection acl_show, acl_reset, acl_policy, acl_add, acl_remove (since 4.0.0)
 121
 122 The ``acl_show'', ``acl_reset'', ``acl_policy'', ``acl_add'', and
 123 ``acl_remove'' commands are deprecated with no replacement. Authorization
 124 for VNC should be performed using the pluggable QAuthZ objects.
 125
 126 @section System emulator devices
 127
 128 @subsection bluetooth (since 3.1)
 129
 130 The bluetooth subsystem is unmaintained since many years and likely bitrotten
 131 quite a bit. It will be removed without replacement unless some users speaks
 132 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
 133 their usecases.
 134
 135 @section System emulator machines
 136
 137 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
 138
 139 These machine types are very old and likely can not be used for live migration
 140 from old QEMU versions anymore. A newer machine type should be used instead.
 141
 142 @subsection prep (PowerPC) (since 3.1)
 143
 144 This machine type uses an unmaintained firmware, broken in lots of ways,
 145 and unable to start post-2004 operating systems. 40p machine type should be
 146 used instead.
 147
 148 @section Device options
 149
 150 @subsection Block device options
 151
 152 @subsubsection "backing": "" (since 2.12.0)
 153
 154 In order to prevent QEMU from automatically opening an image's backing
 155 chain, use ``"backing": null'' instead.
 156
 157 @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
 158
 159 Options for ``rbd'' should be specified according to its runtime options,
 160 like other block drivers.  Legacy parsing of keyvalue pair encoded
 161 filenames is useful to open images with the old format for backing files;
 162 These image files should be updated to use the current format.
 163
 164 Example of legacy encoding:
 165
 166 @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
 167
 168 The above, converted to the current supported format:
 169
 170 @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
 171
 172 @section Related binaries
 173
 174 @subsection qemu-nbd --partition (since 4.0.0)
 175
 176 The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
 177 can only handle MBR partitions, and has never correctly handled
 178 logical partitions beyond partition 5.  If you know the offset and
 179 length of the partition (perhaps by using @code{sfdisk} within the
 180 guest), you can achieve the effect of exporting just that subset of
 181 the disk by use of the @option{--image-opts} option with a raw
 182 blockdev using the @code{offset} and @code{size} parameters layered on
 183 top of any other existing blockdev. For example, if partition 1 is
 184 100MiB long starting at 1MiB, the old command:
 185
 186 @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
 187
 188 can be rewritten as:
 189
 190 @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
 191
 192 Alternatively, the @code{nbdkit} project provides a more powerful
 193 partition filter on top of its nbd plugin, which can be used to select
 194 an arbitrary MBR or GPT partition on top of any other full-image NBD
 195 export.  Using this to rewrite the above example results in:
 196
 197 @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
 198 @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
 199
 200 Note that if you are exposing the export via /dev/nbd0, it is easier
 201 to just export the entire image and then mount only /dev/nbd0p1 than
 202 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
 203 subset of the image.