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 @subsection -realtime (since 4.1)
  76
  77 The @code{-realtime mlock=on|off} argument has been replaced by the
  78 @code{-overcommit mem-lock=on|off} argument.
  79
  80 @section QEMU Machine Protocol (QMP) commands
  81
  82 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
  83
  84 "autoload" parameter is now ignored. All bitmaps are automatically loaded
  85 from qcow2 images.
  86
  87 @subsection query-block result field dirty-bitmaps[i].status (since 4.0)
  88
  89 The ``status'' field of the ``BlockDirtyInfo'' structure, returned by
  90 the query-block command is deprecated. Two new boolean fields,
  91 ``recording'' and ``busy'' effectively replace it.
  92
  93 @subsection query-cpus (since 2.12.0)
  94
  95 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
  96
  97 @subsection query-cpus-fast "arch" output member (since 3.0.0)
  98
  99 The ``arch'' output member of the ``query-cpus-fast'' command is
 100 replaced by the ``target'' output member.
 101
 102 @subsection cpu-add (since 4.0)
 103
 104 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 105 documentation of ``query-hotpluggable-cpus'' for additional
 106 details.
 107
 108 @subsection query-events (since 4.0)
 109
 110 The ``query-events'' command has been superseded by the more powerful
 111 and accurate ``query-qmp-schema'' command.
 112
 113 @subsection chardev client socket with 'wait' option (since 4.0)
 114
 115 Character devices creating sockets in client mode should not specify
 116 the 'wait' field, which is only applicable to sockets in server mode
 117
 118 @section Human Monitor Protocol (HMP) commands
 119
 120 @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
 121
 122 The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
 123 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
 124
 125 @subsection cpu-add (since 4.0)
 126
 127 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 128 documentation of ``query-hotpluggable-cpus'' for additional details.
 129
 130 @subsection acl_show, acl_reset, acl_policy, acl_add, acl_remove (since 4.0.0)
 131
 132 The ``acl_show'', ``acl_reset'', ``acl_policy'', ``acl_add'', and
 133 ``acl_remove'' commands are deprecated with no replacement. Authorization
 134 for VNC should be performed using the pluggable QAuthZ objects.
 135
 136 @section System emulator devices
 137
 138 @subsection bluetooth (since 3.1)
 139
 140 The bluetooth subsystem is unmaintained since many years and likely bitrotten
 141 quite a bit. It will be removed without replacement unless some users speaks
 142 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
 143 their usecases.
 144
 145 @section System emulator machines
 146
 147 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
 148
 149 These machine types are very old and likely can not be used for live migration
 150 from old QEMU versions anymore. A newer machine type should be used instead.
 151
 152 @subsection prep (PowerPC) (since 3.1)
 153
 154 This machine type uses an unmaintained firmware, broken in lots of ways,
 155 and unable to start post-2004 operating systems. 40p machine type should be
 156 used instead.
 157
 158 @section Device options
 159
 160 @subsection Block device options
 161
 162 @subsubsection "backing": "" (since 2.12.0)
 163
 164 In order to prevent QEMU from automatically opening an image's backing
 165 chain, use ``"backing": null'' instead.
 166
 167 @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
 168
 169 Options for ``rbd'' should be specified according to its runtime options,
 170 like other block drivers.  Legacy parsing of keyvalue pair encoded
 171 filenames is useful to open images with the old format for backing files;
 172 These image files should be updated to use the current format.
 173
 174 Example of legacy encoding:
 175
 176 @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
 177
 178 The above, converted to the current supported format:
 179
 180 @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
 181
 182 @section Related binaries
 183
 184 @subsection qemu-nbd --partition (since 4.0.0)
 185
 186 The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
 187 can only handle MBR partitions, and has never correctly handled
 188 logical partitions beyond partition 5.  If you know the offset and
 189 length of the partition (perhaps by using @code{sfdisk} within the
 190 guest), you can achieve the effect of exporting just that subset of
 191 the disk by use of the @option{--image-opts} option with a raw
 192 blockdev using the @code{offset} and @code{size} parameters layered on
 193 top of any other existing blockdev. For example, if partition 1 is
 194 100MiB long starting at 1MiB, the old command:
 195
 196 @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
 197
 198 can be rewritten as:
 199
 200 @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
 201
 202 Alternatively, the @code{nbdkit} project provides a more powerful
 203 partition filter on top of its nbd plugin, which can be used to select
 204 an arbitrary MBR or GPT partition on top of any other full-image NBD
 205 export.  Using this to rewrite the above example results in:
 206
 207 @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
 208 @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
 209
 210 Note that if you are exposing the export via /dev/nbd0, it is easier
 211 to just export the entire image and then mount only /dev/nbd0p1 than
 212 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
 213 subset of the image.