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 -virtioconsole (since 3.0.0)
  41
  42 Option @option{-virtioconsole} has been replaced by
  43 @option{-device virtconsole}.
  44
  45 @subsection -clock (since 3.0.0)
  46
  47 The @code{-clock} option is ignored since QEMU version 1.7.0. There is no
  48 replacement since it is not needed anymore.
  49
  50 @subsection -enable-hax (since 3.0.0)
  51
  52 The @option{-enable-hax} option has been replaced by @option{-accel hax}.
  53 Both options have been introduced in QEMU version 2.9.0.
  54
  55 @subsection -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
  56
  57 The 'file' driver for drives is no longer appropriate for character or host
  58 devices and will only accept regular files (S_IFREG). The correct driver
  59 for these file types is 'host_cdrom' or 'host_device' as appropriate.
  60
  61 @subsection -net ...,name=@var{name} (since 3.1)
  62
  63 The @option{name} parameter of the @option{-net} option is a synonym
  64 for the @option{id} parameter, which should now be used instead.
  65
  66 @subsection -smp (invalid topologies) (since 3.1)
  67
  68 CPU topology properties should describe whole machine topology including
  69 possible CPUs.
  70
  71 However, historically it was possible to start QEMU with an incorrect topology
  72 where @math{@var{n} <= @var{sockets} * @var{cores} * @var{threads} < @var{maxcpus}},
  73 which could lead to an incorrect topology enumeration by the guest.
  74 Support for invalid topologies will be removed, the user must ensure
  75 topologies described with -smp include all possible cpus, i.e.
  76   @math{@var{sockets} * @var{cores} * @var{threads} = @var{maxcpus}}.
  77
  78 @section QEMU Machine Protocol (QMP) commands
  79
  80 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
  81
  82 "autoload" parameter is now ignored. All bitmaps are automatically loaded
  83 from qcow2 images.
  84
  85 @subsection query-cpus (since 2.12.0)
  86
  87 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
  88
  89 @subsection query-cpus-fast "arch" output member (since 3.0.0)
  90
  91 The ``arch'' output member of the ``query-cpus-fast'' command is
  92 replaced by the ``target'' output member.
  93
  94 @subsection cpu-add (since 4.0)
  95
  96 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
  97 documentation of ``query-hotpluggable-cpus'' for additional
  98 details.
  99
 100 @section Human Monitor Protocol (HMP) commands
 101
 102 @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
 103
 104 The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
 105 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
 106
 107 @subsection cpu-add (since 4.0)
 108
 109 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''.  See
 110 documentation of ``query-hotpluggable-cpus'' for additional details.
 111
 112 @section System emulator devices
 113
 114 @subsection bluetooth (since 3.1)
 115
 116 The bluetooth subsystem is unmaintained since many years and likely bitrotten
 117 quite a bit. It will be removed without replacement unless some users speaks
 118 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
 119 their usecases.
 120
 121 @section System emulator machines
 122
 123 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
 124
 125 These machine types are very old and likely can not be used for live migration
 126 from old QEMU versions anymore. A newer machine type should be used instead.
 127
 128 @subsection prep (PowerPC) (since 3.1)
 129
 130 This machine type uses an unmaintained firmware, broken in lots of ways,
 131 and unable to start post-2004 operating systems. 40p machine type should be
 132 used instead.
 133
 134 @section Device options
 135
 136 @subsection Block device options
 137
 138 @subsubsection "backing": "" (since 2.12.0)
 139
 140 In order to prevent QEMU from automatically opening an image's backing
 141 chain, use ``"backing": null'' instead.
 142
 143 @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
 144
 145 Options for ``rbd'' should be specified according to its runtime options,
 146 like other block drivers.  Legacy parsing of keyvalue pair encoded
 147 filenames is useful to open images with the old format for backing files;
 148 These image files should be updated to use the current format.
 149
 150 Example of legacy encoding:
 151
 152 @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
 153
 154 The above, converted to the current supported format:
 155
 156 @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
 157
 158 @section Related binaries
 159
 160 @subsection qemu-nbd --partition (since 4.0.0)
 161
 162 The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
 163 can only handle MBR partitions, and has never correctly handled
 164 logical partitions beyond partition 5.  If you know the offset and
 165 length of the partition (perhaps by using @code{sfdisk} within the
 166 guest), you can achieve the effect of exporting just that subset of
 167 the disk by use of the @option{--image-opts} option with a raw
 168 blockdev using the @code{offset} and @code{size} parameters layered on
 169 top of any other existing blockdev. For example, if partition 1 is
 170 100MiB long starting at 1MiB, the old command:
 171
 172 @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
 173
 174 can be rewritten as:
 175
 176 @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
 177
 178 Alternatively, the @code{nbdkit} project provides a more powerful
 179 partition filter on top of its nbd plugin, which can be used to select
 180 an arbitrary MBR or GPT partition on top of any other full-image NBD
 181 export.  Using this to rewrite the above example results in:
 182
 183 @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
 184 @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
 185
 186 Note that if you are exposing the export via /dev/nbd0, it is easier
 187 to just export the entire image and then mount only /dev/nbd0p1 than
 188 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a
 189 subset of the image.