1 @node Deprecated features
2 @appendix Deprecated features
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.
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.
17 What follows is a list of all features currently marked as
20 @section System emulator command line arguments
22 @subsection -machine enforce-config-section=on|off (since 3.1)
24 The @option{enforce-config-section} parameter is replaced by the
25 @option{-global migration.send-configuration=@var{on|off}} option.
27 @subsection -no-kvm (since 1.3.0)
29 The ``-no-kvm'' argument is now a synonym for setting
30 ``-machine accel=tcg''.
32 @subsection -usbdevice (since 2.10.0)
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.
40 @subsection -drive file=json:@{...@{'driver':'file'@}@} (since 3.0)
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.
46 @subsection -net ...,name=@var{name} (since 3.1)
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.
51 @subsection -smp (invalid topologies) (since 3.1)
53 CPU topology properties should describe whole machine topology including
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}}.
63 @subsection -vnc acl (since 4.0.0)
65 The @code{acl} option to the @code{-vnc} argument has been replaced
66 by the @code{tls-authz} and @code{sasl-authz} options.
68 @subsection QEMU_AUDIO_ environment variables and -audio-help (since 4.0)
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.
75 @subsection -mon ...,control=readline,pretty=on|off (since 4.1)
77 The @code{pretty=on|off} switch has no effect for HMP monitors, but is
78 silently ignored. Using the switch with HMP monitors will become an
81 @subsection -realtime (since 4.1)
83 The @code{-realtime mlock=on|off} argument has been replaced by the
84 @code{-overcommit mem-lock=on|off} argument.
86 @subsection -virtfs_synth (since 4.1)
88 The ``-virtfs_synth'' argument is now deprecated. Please use ``-fsdev synth''
89 and ``-device virtio-9p-...'' instead.
91 @section QEMU Machine Protocol (QMP) commands
93 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)
95 "autoload" parameter is now ignored. All bitmaps are automatically loaded
98 @subsection query-block result field dirty-bitmaps[i].status (since 4.0)
100 The ``status'' field of the ``BlockDirtyInfo'' structure, returned by
101 the query-block command is deprecated. Two new boolean fields,
102 ``recording'' and ``busy'' effectively replace it.
104 @subsection query-cpus (since 2.12.0)
106 The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command.
108 @subsection query-cpus-fast "arch" output member (since 3.0.0)
110 The ``arch'' output member of the ``query-cpus-fast'' command is
111 replaced by the ``target'' output member.
113 @subsection cpu-add (since 4.0)
115 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See
116 documentation of ``query-hotpluggable-cpus'' for additional
119 @subsection query-events (since 4.0)
121 The ``query-events'' command has been superseded by the more powerful
122 and accurate ``query-qmp-schema'' command.
124 @subsection chardev client socket with 'wait' option (since 4.0)
126 Character devices creating sockets in client mode should not specify
127 the 'wait' field, which is only applicable to sockets in server mode
129 @section Human Monitor Protocol (HMP) commands
131 @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1)
133 The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and
134 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}.
136 @subsection cpu-add (since 4.0)
138 Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See
139 documentation of ``query-hotpluggable-cpus'' for additional details.
141 @subsection acl_show, acl_reset, acl_policy, acl_add, acl_remove (since 4.0.0)
143 The ``acl_show'', ``acl_reset'', ``acl_policy'', ``acl_add'', and
144 ``acl_remove'' commands are deprecated with no replacement. Authorization
145 for VNC should be performed using the pluggable QAuthZ objects.
147 @section System emulator CPUS
149 @subsection RISC-V ISA CPUs (since 4.1)
151 The RISC-V cpus with the ISA version in the CPU name have been depcreated. The
152 four CPUs are: ``rv32gcsu-v1.9.1``, ``rv32gcsu-v1.10.0``, ``rv64gcsu-v1.9.1`` and
153 ``rv64gcsu-v1.10.0``. Instead the version can be specified via the CPU ``priv_spec``
154 option when using the ``rv32`` or ``rv64`` CPUs.
156 @subsection RISC-V ISA CPUs (since 4.1)
158 The RISC-V no MMU cpus have been depcreated. The two CPUs: ``rv32imacu-nommu`` and
159 ``rv64imacu-nommu`` should no longer be used. Instead the MMU status can be specified
160 via the CPU ``mmu`` option when using the ``rv32`` or ``rv64`` CPUs.
162 @section System emulator devices
164 @subsection bluetooth (since 3.1)
166 The bluetooth subsystem is unmaintained since many years and likely bitrotten
167 quite a bit. It will be removed without replacement unless some users speaks
168 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
171 @section System emulator machines
173 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)
175 These machine types are very old and likely can not be used for live migration
176 from old QEMU versions anymore. A newer machine type should be used instead.
178 @subsection prep (PowerPC) (since 3.1)
180 This machine type uses an unmaintained firmware, broken in lots of ways,
181 and unable to start post-2004 operating systems. 40p machine type should be
184 @subsection spike_v1.9.1 and spike_v1.10 (since 4.1)
186 The version specific Spike machines have been deprecated in favour of the
187 generic ``spike`` machine. If you need to specify an older version of the RISC-V
188 spec you can use the ``-cpu rv64gcsu,priv_spec=v1.9.1`` command line argument.
190 @section Device options
192 @subsection Block device options
194 @subsubsection "backing": "" (since 2.12.0)
196 In order to prevent QEMU from automatically opening an image's backing
197 chain, use ``"backing": null'' instead.
199 @subsubsection rbd keyvalue pair encoded filenames: "" (since 3.1.0)
201 Options for ``rbd'' should be specified according to its runtime options,
202 like other block drivers. Legacy parsing of keyvalue pair encoded
203 filenames is useful to open images with the old format for backing files;
204 These image files should be updated to use the current format.
206 Example of legacy encoding:
208 @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}}
210 The above, converted to the current supported format:
212 @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}}
214 @section Related binaries
216 @subsection qemu-nbd --partition (since 4.0.0)
218 The ``qemu-nbd --partition $digit'' code (also spelled @option{-P})
219 can only handle MBR partitions, and has never correctly handled
220 logical partitions beyond partition 5. If you know the offset and
221 length of the partition (perhaps by using @code{sfdisk} within the
222 guest), you can achieve the effect of exporting just that subset of
223 the disk by use of the @option{--image-opts} option with a raw
224 blockdev using the @code{offset} and @code{size} parameters layered on
225 top of any other existing blockdev. For example, if partition 1 is
226 100MiB long starting at 1MiB, the old command:
228 @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2}
232 @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2}
234 Alternatively, the @code{nbdkit} project provides a more powerful
235 partition filter on top of its nbd plugin, which can be used to select
236 an arbitrary MBR or GPT partition on top of any other full-image NBD
237 export. Using this to rewrite the above example results in:
239 @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &}
240 @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1}
242 Note that if you are exposing the export via /dev/nbd0, it is easier
243 to just export the entire image and then mount only /dev/nbd0p1 than
244 it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a