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  99 The ``query-events'' command has been superseded by the more powerful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 107 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.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