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1 Deprecated features
2 ===================
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 section. The feature will remain functional for the
7 release in which it was deprecated and one further release. After these two
8 releases, the feature is liable to be removed. Deprecated features may also
9 generate warnings on the console when QEMU starts up, or if activated via a
10 monitor command, however, this is not a mandatory requirement.
11
12 Prior to the 2.10.0 release there was no official policy on how
13 long features would be deprecated prior to their removal, nor
14 any documented list of which features were deprecated. Thus
15 any features deprecated prior to 2.10.0 will be treated as if
16 they were first deprecated in the 2.10.0 release.
17
18 What follows is a list of all features currently marked as
19 deprecated.
20
21 System emulator command line arguments
22 --------------------------------------
23
24 ``-usbdevice`` (since 2.10.0)
25 '''''''''''''''''''''''''''''
26
27 The ``-usbdevice DEV`` argument is now a synonym for setting
28 the ``-device usb-DEV`` argument instead. The deprecated syntax
29 would automatically enable USB support on the machine type.
30 If using the new syntax, USB support must be explicitly
31 enabled via the ``-machine usb=on`` argument.
32
33 ``-drive file=json:{...{'driver':'file'}}`` (since 3.0)
34 '''''''''''''''''''''''''''''''''''''''''''''''''''''''
35
36 The 'file' driver for drives is no longer appropriate for character or host
37 devices and will only accept regular files (S_IFREG). The correct driver
38 for these file types is 'host_cdrom' or 'host_device' as appropriate.
39
40 ``-vnc acl`` (since 4.0.0)
41 ''''''''''''''''''''''''''
42
43 The ``acl`` option to the ``-vnc`` argument has been replaced
44 by the ``tls-authz`` and ``sasl-authz`` options.
45
46 ``QEMU_AUDIO_`` environment variables and ``-audio-help`` (since 4.0)
47 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
48
49 The ``-audiodev`` argument is now the preferred way to specify audio
50 backend settings instead of environment variables. To ease migration to
51 the new format, the ``-audiodev-help`` option can be used to convert
52 the current values of the environment variables to ``-audiodev`` options.
53
54 Creating sound card devices and vnc without ``audiodev=`` property (since 4.2)
55 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
56
57 When not using the deprecated legacy audio config, each sound card
58 should specify an ``audiodev=`` property. Additionally, when using
59 vnc, you should specify an ``audiodev=`` property if you plan to
60 transmit audio through the VNC protocol.
61
62 Creating sound card devices using ``-soundhw`` (since 5.1)
63 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
64
65 Sound card devices should be created using ``-device`` instead. The
66 names are the same for most devices. The exceptions are ``hda`` which
67 needs two devices (``-device intel-hda -device hda-duplex``) and
68 ``pcspk`` which can be activated using ``-machine
69 pcspk-audiodev=<name>``.
70
71 ``-mon ...,control=readline,pretty=on|off`` (since 4.1)
72 '''''''''''''''''''''''''''''''''''''''''''''''''''''''
73
74 The ``pretty=on|off`` switch has no effect for HMP monitors, but is
75 silently ignored. Using the switch with HMP monitors will become an
76 error in the future.
77
78 RISC-V ``-bios`` (since 5.1)
79 ''''''''''''''''''''''''''''
80
81 QEMU 4.1 introduced support for the -bios option in QEMU for RISC-V for the
82 RISC-V virt machine and sifive_u machine. QEMU 4.1 had no changes to the
83 default behaviour to avoid breakages.
84
85 QEMU 5.1 changes the default behaviour from ``-bios none`` to ``-bios default``.
86
87 QEMU 5.1 has three options:
88 1. ``-bios default`` - This is the current default behavior if no -bios option
89 is included. This option will load the default OpenSBI firmware automatically.
90 The firmware is included with the QEMU release and no user interaction is
91 required. All a user needs to do is specify the kernel they want to boot
92 with the -kernel option
93 2. ``-bios none`` - QEMU will not automatically load any firmware. It is up
94 to the user to load all the images they need.
95 3. ``-bios <file>`` - Tells QEMU to load the specified file as the firmwrae.
96
97 ``Configuring floppies with ``-global``
98 '''''''''''''''''''''''''''''''''''''''
99
100 Use ``-device floppy,...`` instead:
101 ::
102
103 -global isa-fdc.driveA=...
104 -global sysbus-fdc.driveA=...
105 -global SUNW,fdtwo.drive=...
106
107 become
108 ::
109
110 -device floppy,unit=0,drive=...
111
112 and
113 ::
114
115 -global isa-fdc.driveB=...
116 -global sysbus-fdc.driveB=...
117
118 become
119 ::
120
121 -device floppy,unit=1,drive=...
122
123 ``-drive`` with bogus interface type
124 ''''''''''''''''''''''''''''''''''''
125
126 Drives with interface types other than ``if=none`` are for onboard
127 devices. It is possible to use drives the board doesn't pick up with
128 -device. This usage is now deprecated. Use ``if=none`` instead.
129
130
131 QEMU Machine Protocol (QMP) commands
132 ------------------------------------
133
134 ``blockdev-open-tray``, ``blockdev-close-tray`` argument ``device`` (since 2.8.0)
135 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
136
137 Use argument ``id`` instead.
138
139 ``eject`` argument ``device`` (since 2.8.0)
140 '''''''''''''''''''''''''''''''''''''''''''
141
142 Use argument ``id`` instead.
143
144 ``blockdev-change-medium`` argument ``device`` (since 2.8.0)
145 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
146
147 Use argument ``id`` instead.
148
149 ``block_set_io_throttle`` argument ``device`` (since 2.8.0)
150 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
151
152 Use argument ``id`` instead.
153
154 ``migrate_set_downtime`` and ``migrate_set_speed`` (since 2.8.0)
155 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
156
157 Use ``migrate-set-parameters`` instead.
158
159 ``query-named-block-nodes`` result ``encryption_key_missing`` (since 2.10.0)
160 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
161
162 Always false.
163
164 ``query-block`` result ``inserted.encryption_key_missing`` (since 2.10.0)
165 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
166
167 Always false.
168
169 ``blockdev-add`` empty string argument ``backing`` (since 2.10.0)
170 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
171
172 Use argument value ``null`` instead.
173
174 ``migrate-set-cache-size`` and ``query-migrate-cache-size`` (since 2.11.0)
175 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
176
177 Use ``migrate-set-parameters`` and ``query-migrate-parameters`` instead.
178
179 ``block-commit`` arguments ``base`` and ``top`` (since 3.1.0)
180 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
181
182 Use arguments ``base-node`` and ``top-node`` instead.
183
184 ``object-add`` option ``props`` (since 5.0)
185 '''''''''''''''''''''''''''''''''''''''''''
186
187 Specify the properties for the object as top-level arguments instead.
188
189 ``query-named-block-nodes`` and ``query-block`` result dirty-bitmaps[i].status (since 4.0)
190 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
191
192 The ``status`` field of the ``BlockDirtyInfo`` structure, returned by
193 these commands is deprecated. Two new boolean fields, ``recording`` and
194 ``busy`` effectively replace it.
195
196 ``query-block`` result field ``dirty-bitmaps`` (Since 4.2)
197 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
198
199 The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by
200 the query-block command is itself now deprecated. The ``dirty-bitmaps``
201 field of the ``BlockDeviceInfo`` struct should be used instead, which is the
202 type of the ``inserted`` field in query-block replies, as well as the
203 type of array items in query-named-block-nodes.
204
205 Since the ``dirty-bitmaps`` field is optionally present in both the old and
206 new locations, clients must use introspection to learn where to anticipate
207 the field if/when it does appear in command output.
208
209 ``query-cpus`` (since 2.12.0)
210 '''''''''''''''''''''''''''''
211
212 The ``query-cpus`` command is replaced by the ``query-cpus-fast`` command.
213
214 ``query-cpus-fast`` ``arch`` output member (since 3.0.0)
215 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''
216
217 The ``arch`` output member of the ``query-cpus-fast`` command is
218 replaced by the ``target`` output member.
219
220 ``query-events`` (since 4.0)
221 ''''''''''''''''''''''''''''
222
223 The ``query-events`` command has been superseded by the more powerful
224 and accurate ``query-qmp-schema`` command.
225
226 chardev client socket with ``wait`` option (since 4.0)
227 ''''''''''''''''''''''''''''''''''''''''''''''''''''''
228
229 Character devices creating sockets in client mode should not specify
230 the 'wait' field, which is only applicable to sockets in server mode
231
232 ``nbd-server-add`` and ``nbd-server-remove`` (since 5.2)
233 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''
234
235 Use the more generic commands ``block-export-add`` and ``block-export-del``
236 instead. As part of this deprecation, where ``nbd-server-add`` used a
237 single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
238
239 Human Monitor Protocol (HMP) commands
240 -------------------------------------
241
242 ``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, ``acl_remove`` (since 4.0.0)
243 ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
244
245 The ``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, and
246 ``acl_remove`` commands are deprecated with no replacement. Authorization
247 for VNC should be performed using the pluggable QAuthZ objects.
248
249 System emulator CPUS
250 --------------------
251
252 ``moxie`` CPU (since 5.2.0)
253 '''''''''''''''''''''''''''
254
255 The ``moxie`` guest CPU support is deprecated and will be removed in
256 a future version of QEMU. It's unclear whether anybody is still using
257 CPU emulation in QEMU, and there are no test images available to make
258 sure that the code is still working.
259
260 ``lm32`` CPUs (since 5.2.0)
261 '''''''''''''''''''''''''''
262
263 The ``lm32`` guest CPU support is deprecated and will be removed in
264 a future version of QEMU. The only public user of this architecture
265 was the milkymist project, which has been dead for years; there was
266 never an upstream Linux port.
267
268 ``unicore32`` CPUs (since 5.2.0)
269 ''''''''''''''''''''''''''''''''
270
271 The ``unicore32`` guest CPU support is deprecated and will be removed in
272 a future version of QEMU. Support for this CPU was removed from the
273 upstream Linux kernel, and there is no available upstream toolchain
274 to build binaries for it.
275
276 ``Icelake-Client`` CPU Model (since 5.2.0)
277 ''''''''''''''''''''''''''''''''''''''''''
278
279 ``Icelake-Client`` CPU Models are deprecated. Use ``Icelake-Server`` CPU
280 Models instead.
281
282 MIPS ``I7200`` CPU Model (since 5.2)
283 ''''''''''''''''''''''''''''''''''''
284
285 The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
286 (the ISA has never been upstreamed to a compiler toolchain). Therefore
287 this CPU is also deprecated.
288
289 System emulator devices
290 -----------------------
291
292 ``ide-drive`` (since 4.2)
293 '''''''''''''''''''''''''
294
295 The 'ide-drive' device is deprecated. Users should use 'ide-hd' or
296 'ide-cd' as appropriate to get an IDE hard disk or CD-ROM as needed.
297
298 ``scsi-disk`` (since 4.2)
299 '''''''''''''''''''''''''
300
301 The 'scsi-disk' device is deprecated. Users should use 'scsi-hd' or
302 'scsi-cd' as appropriate to get a SCSI hard disk or CD-ROM as needed.
303
304 System emulator machines
305 ------------------------
306
307 ``pc-1.0``, ``pc-1.1``, ``pc-1.2`` and ``pc-1.3`` (since 5.0)
308 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
309
310 These machine types are very old and likely can not be used for live migration
311 from old QEMU versions anymore. A newer machine type should be used instead.
312
313 Raspberry Pi ``raspi2`` and ``raspi3`` machines (since 5.2)
314 '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
315
316 The Raspberry Pi machines come in various models (A, A+, B, B+). To be able
317 to distinguish which model QEMU is implementing, the ``raspi2`` and ``raspi3``
318 machines have been renamed ``raspi2b`` and ``raspi3b``.
319
320 Device options
321 --------------
322
323 Emulated device options
324 '''''''''''''''''''''''
325
326 ``-device virtio-blk,scsi=on|off`` (since 5.0.0)
327 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
328
329 The virtio-blk SCSI passthrough feature is a legacy VIRTIO feature. VIRTIO 1.0
330 and later do not support it because the virtio-scsi device was introduced for
331 full SCSI support. Use virtio-scsi instead when SCSI passthrough is required.
332
333 Note this also applies to ``-device virtio-blk-pci,scsi=on|off``, which is an
334 alias.
335
336 Block device options
337 ''''''''''''''''''''
338
339 ``"backing": ""`` (since 2.12.0)
340 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
341
342 In order to prevent QEMU from automatically opening an image's backing
343 chain, use ``"backing": null`` instead.
344
345 ``rbd`` keyvalue pair encoded filenames: ``""`` (since 3.1.0)
346 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
347
348 Options for ``rbd`` should be specified according to its runtime options,
349 like other block drivers. Legacy parsing of keyvalue pair encoded
350 filenames is useful to open images with the old format for backing files;
351 These image files should be updated to use the current format.
352
353 Example of legacy encoding::
354
355 json:{"file.driver":"rbd", "file.filename":"rbd:rbd/name"}
356
357 The above, converted to the current supported format::
358
359 json:{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"}
360
361 ``sheepdog`` driver (since 5.2.0)
362 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
363
364 The ``sheepdog`` block device driver is deprecated. The corresponding upstream
365 server project is no longer actively maintained. Users are recommended to switch
366 to an alternative distributed block device driver such as RBD. The
367 ``qemu-img convert`` command can be used to liberate existing data by moving
368 it out of sheepdog volumes into an alternative storage backend.
369
370 linux-user mode CPUs
371 --------------------
372
373 ``tilegx`` CPUs (since 5.1.0)
374 '''''''''''''''''''''''''''''
375
376 The ``tilegx`` guest CPU support (which was only implemented in
377 linux-user mode) is deprecated and will be removed in a future version
378 of QEMU. Support for this CPU was removed from the upstream Linux
379 kernel in 2018, and has also been dropped from glibc.
380
381 ``ppc64abi32`` CPUs (since 5.2.0)
382 '''''''''''''''''''''''''''''''''
383
384 The ``ppc64abi32`` architecture has a number of issues which regularly
385 trip up our CI testing and is suspected to be quite broken. For that
386 reason the maintainers strongly suspect no one actually uses it.
387
388 MIPS ``I7200`` CPU (since 5.2)
389 ''''''''''''''''''''''''''''''
390
391 The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
392 (the ISA has never been upstreamed to a compiler toolchain). Therefore
393 this CPU is also deprecated.
394
395 Related binaries
396 ----------------
397
398 qemu-img amend to adjust backing file (since 5.1)
399 '''''''''''''''''''''''''''''''''''''''''''''''''
400
401 The use of ``qemu-img amend`` to modify the name or format of a qcow2
402 backing image is deprecated; this functionality was never fully
403 documented or tested, and interferes with other amend operations that
404 need access to the original backing image (such as deciding whether a
405 v3 zero cluster may be left unallocated when converting to a v2
406 image). Rather, any changes to the backing chain should be performed
407 with ``qemu-img rebase -u`` either before or after the remaining
408 changes being performed by amend, as appropriate.
409
410 qemu-img backing file without format (since 5.1)
411 ''''''''''''''''''''''''''''''''''''''''''''''''
412
413 The use of ``qemu-img create``, ``qemu-img rebase``, or ``qemu-img
414 convert`` to create or modify an image that depends on a backing file
415 now recommends that an explicit backing format be provided. This is
416 for safety: if QEMU probes a different format than what you thought,
417 the data presented to the guest will be corrupt; similarly, presenting
418 a raw image to a guest allows a potential security exploit if a future
419 probe sees a non-raw image based on guest writes.
420
421 To avoid the warning message, or even future refusal to create an
422 unsafe image, you must pass ``-o backing_fmt=`` (or the shorthand
423 ``-F`` during create) to specify the intended backing format. You may
424 use ``qemu-img rebase -u`` to retroactively add a backing format to an
425 existing image. However, be aware that there are already potential
426 security risks to blindly using ``qemu-img info`` to probe the format
427 of an untrusted backing image, when deciding what format to add into
428 an existing image.
429
430 Backwards compatibility
431 -----------------------
432
433 Runnability guarantee of CPU models (since 4.1.0)
434 '''''''''''''''''''''''''''''''''''''''''''''''''
435
436 Previous versions of QEMU never changed existing CPU models in
437 ways that introduced additional host software or hardware
438 requirements to the VM. This allowed management software to
439 safely change the machine type of an existing VM without
440 introducing new requirements ("runnability guarantee"). This
441 prevented CPU models from being updated to include CPU
442 vulnerability mitigations, leaving guests vulnerable in the
443 default configuration.
444
445 The CPU model runnability guarantee won't apply anymore to
446 existing CPU models. Management software that needs runnability
447 guarantees must resolve the CPU model aliases using the
448 ``alias-of`` field returned by the ``query-cpu-definitions`` QMP
449 command.
450
451 While those guarantees are kept, the return value of
452 ``query-cpu-definitions`` will have existing CPU model aliases
453 point to a version that doesn't break runnability guarantees
454 (specifically, version 1 of those CPU models). In future QEMU
455 versions, aliases will point to newer CPU model versions
456 depending on the machine type, so management software must
457 resolve CPU model aliases before starting a virtual machine.
458
459 Guest Emulator ISAs
460 -------------------
461
462 nanoMIPS ISA
463 ''''''''''''
464
465 The ``nanoMIPS`` ISA has never been upstreamed to any compiler toolchain.
466 As it is hard to generate binaries for it, declare it deprecated.