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 @section QEMU Machine Protocol (QMP) commands
  69
  70 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
  71
  72 "autoload" parameter is now ignored. All bitmaps are automatically loaded
  73 from qcow2 images.
  74
  75 @subsection query-block result field dirty-bitmaps[i].status (since 4.0)
  76
  77 The ``status'' field of the ``BlockDirtyInfo'' structure, returned by
  78 the query-block command is deprecated. Two new boolean fields,
  79 ``recording'' and ``busy'' effectively replace it.
  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 @subsection query-events (since 4.0)
  97
  98 The ``query-events'' command has been superseded by the more powerful
  99 and accurate ``query-qmp-schema'' command.
 100
 101 @section Human Monitor Protocol (HMP) commands
 102
 103 @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
 104
 105 The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
 106 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
 107
 108 @subsection cpu-add (since 4.0)
 109
 110 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 111 documentation of ``query-hotpluggable-cpus'' for additional details.
 112
 113 @subsection acl_show, acl_reset, acl_policy, acl_add, acl_remove (since 4.0.0)
 114
 115 The ``acl_show'', ``acl_reset'', ``acl_policy'', ``acl_add'', and
 116 ``acl_remove'' commands are deprecated with no replacement. Authorization
 117 for VNC should be performed using the pluggable QAuthZ objects.
 118
 119 @section System emulator devices
 120
 121 @subsection bluetooth (since 3.1)
 122
 123 The bluetooth subsystem is unmaintained since many years and likely bitrotten
 124 quite a bit. It will be removed without replacement unless some users speaks
 125 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
 126 their usecases.
 127
 128 @section System emulator machines
 129
 130 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
 131
 132 These machine types are very old and likely can not be used for live migration
 133 from old QEMU versions anymore. A newer machine type should be used instead.
 134
 135 @subsection prep (PowerPC) (since 3.1)
 136
 137 This machine type uses an unmaintained firmware, broken in lots of ways,
 138 and unable to start post-2004 operating systems. 40p machine type should be
 139 used instead.
 140
 141 @section Device options
 142
 143 @subsection Block device options
 144
 145 @subsubsection "backing": "" (since 2.12.0)
 146
 147 In order to prevent QEMU from automatically opening an image's backing
 148 chain, use ``"backing": null'' instead.
 149
 150 @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
 151
 152 Options for ``rbd'' should be specified according to its runtime options,
 153 like other block drivers.  Legacy parsing of keyvalue pair encoded
 154 filenames is useful to open images with the old format for backing files;
 155 These image files should be updated to use the current format.
 156
 157 Example of legacy encoding:
 158
 159 @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
 160
 161 The above, converted to the current supported format:
 162
 163 @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
 164
 165 @section Related binaries
 166
 167 @subsection qemu-nbd --partition (since 4.0.0)
 168
 169 The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
 170 can only handle MBR partitions, and has never correctly handled
 171 logical partitions beyond partition 5.  If you know the offset and
 172 length of the partition (perhaps by using @code{sfdisk} within the
 173 guest), you can achieve the effect of exporting just that subset of
 174 the disk by use of the @option{--image-opts} option with a raw
 175 blockdev using the @code{offset} and @code{size} parameters layered on
 176 top of any other existing blockdev. For example, if partition 1 is
 177 100MiB long starting at 1MiB, the old command:
 178
 179 @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
 180
 181 can be rewritten as:
 182
 183 @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
 184
 185 Alternatively, the @code{nbdkit} project provides a more powerful
 186 partition filter on top of its nbd plugin, which can be used to select
 187 an arbitrary MBR or GPT partition on top of any other full-image NBD
 188 export.  Using this to rewrite the above example results in:
 189
 190 @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
 191 @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
 192
 193 Note that if you are exposing the export via /dev/nbd0, it is easier
 194 to just export the entire image and then mount only /dev/nbd0p1 than
 195 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
 196 subset of the image.