1.. _Deprecated features: 2 3Deprecated features 4=================== 5 6In general features are intended to be supported indefinitely once 7introduced into QEMU. In the event that a feature needs to be removed, 8it will be listed in this section. The feature will remain functional for the 9release in which it was deprecated and one further release. After these two 10releases, the feature is liable to be removed. Deprecated features may also 11generate warnings on the console when QEMU starts up, or if activated via a 12monitor command, however, this is not a mandatory requirement. 13 14Prior to the 2.10.0 release there was no official policy on how 15long features would be deprecated prior to their removal, nor 16any documented list of which features were deprecated. Thus 17any features deprecated prior to 2.10.0 will be treated as if 18they were first deprecated in the 2.10.0 release. 19 20What follows is a list of all features currently marked as 21deprecated. 22 23System emulator command line arguments 24-------------------------------------- 25 26``QEMU_AUDIO_`` environment variables and ``-audio-help`` (since 4.0) 27''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 28 29The ``-audiodev`` argument is now the preferred way to specify audio 30backend settings instead of environment variables. To ease migration to 31the new format, the ``-audiodev-help`` option can be used to convert 32the current values of the environment variables to ``-audiodev`` options. 33 34Creating sound card devices and vnc without ``audiodev=`` property (since 4.2) 35'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 36 37When not using the deprecated legacy audio config, each sound card 38should specify an ``audiodev=`` property. Additionally, when using 39vnc, you should specify an ``audiodev=`` property if you plan to 40transmit audio through the VNC protocol. 41 42Creating sound card devices using ``-soundhw`` (since 5.1) 43'''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 44 45Sound card devices should be created using ``-device`` instead. The 46names are the same for most devices. The exceptions are ``hda`` which 47needs two devices (``-device intel-hda -device hda-duplex``) and 48``pcspk`` which can be activated using ``-machine 49pcspk-audiodev=<name>``. 50 51``-chardev`` backend aliases ``tty`` and ``parport`` (since 6.0) 52'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 53 54``tty`` and ``parport`` are aliases that will be removed. Instead, the 55actual backend names ``serial`` and ``parallel`` should be used. 56 57Short-form boolean options (since 6.0) 58'''''''''''''''''''''''''''''''''''''' 59 60Boolean options such as ``share=on``/``share=off`` could be written 61in short form as ``share`` and ``noshare``. This is now deprecated 62and will cause a warning. 63 64``delay`` option for socket character devices (since 6.0) 65''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 66 67The replacement for the ``nodelay`` short-form boolean option is ``nodelay=on`` 68rather than ``delay=off``. 69 70``--enable-fips`` (since 6.0) 71''''''''''''''''''''''''''''' 72 73This option restricts usage of certain cryptographic algorithms when 74the host is operating in FIPS mode. 75 76If FIPS compliance is required, QEMU should be built with the ``libgcrypt`` 77library enabled as a cryptography provider. 78 79Neither the ``nettle`` library, or the built-in cryptography provider are 80supported on FIPS enabled hosts. 81 82``-writeconfig`` (since 6.0) 83''''''''''''''''''''''''''''' 84 85The ``-writeconfig`` option is not able to serialize the entire contents 86of the QEMU command line. It is thus considered a failed experiment 87and deprecated, with no current replacement. 88 89Userspace local APIC with KVM (x86, since 6.0) 90'''''''''''''''''''''''''''''''''''''''''''''' 91 92Using ``-M kernel-irqchip=off`` with x86 machine types that include a local 93APIC is deprecated. The ``split`` setting is supported, as is using 94``-M kernel-irqchip=off`` with the ISA PC machine type. 95 96hexadecimal sizes with scaling multipliers (since 6.0) 97'''''''''''''''''''''''''''''''''''''''''''''''''''''' 98 99Input parameters that take a size value should only use a size suffix 100(such as 'k' or 'M') when the base is written in decimal, and not when 101the value is hexadecimal. That is, '0x20M' is deprecated, and should 102be written either as '32M' or as '0x2000000'. 103 104``-spice password=string`` (since 6.0) 105'''''''''''''''''''''''''''''''''''''' 106 107This option is insecure because the SPICE password remains visible in 108the process listing. This is replaced by the new ``password-secret`` 109option which lets the password be securely provided on the command 110line using a ``secret`` object instance. 111 112``opened`` property of ``rng-*`` objects (since 6.0) 113'''''''''''''''''''''''''''''''''''''''''''''''''''' 114 115The only effect of specifying ``opened=on`` in the command line or QMP 116``object-add`` is that the device is opened immediately, possibly before all 117other options have been processed. This will either have no effect (if 118``opened`` was the last option) or cause errors. The property is therefore 119useless and should not be specified. 120 121``loaded`` property of ``secret`` and ``secret_keyring`` objects (since 6.0) 122'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 123 124The only effect of specifying ``loaded=on`` in the command line or QMP 125``object-add`` is that the secret is loaded immediately, possibly before all 126other options have been processed. This will either have no effect (if 127``loaded`` was the last option) or cause options to be effectively ignored as 128if they were not given. The property is therefore useless and should not be 129specified. 130 131``-display sdl,window_close=...`` (since 6.1) 132''''''''''''''''''''''''''''''''''''''''''''' 133 134Use ``-display sdl,window-close=...`` instead (i.e. with a minus instead of 135an underscore between "window" and "close"). 136 137``-no-quit`` (since 6.1) 138'''''''''''''''''''''''' 139 140The ``-no-quit`` is a synonym for ``-display ...,window-close=off`` which 141should be used instead. 142 143``-alt-grab`` and ``-display sdl,alt_grab=on`` (since 6.2) 144'''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 145 146Use ``-display sdl,grab-mod=lshift-lctrl-lalt`` instead. 147 148``-ctrl-grab`` and ``-display sdl,ctrl_grab=on`` (since 6.2) 149'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 150 151Use ``-display sdl,grab-mod=rctrl`` instead. 152 153``-sdl`` (since 6.2) 154'''''''''''''''''''' 155 156Use ``-display sdl`` instead. 157 158``-curses`` (since 6.2) 159''''''''''''''''''''''' 160 161Use ``-display curses`` instead. 162 163 164Plugin argument passing through ``arg=<string>`` (since 6.1) 165'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 166 167Passing TCG plugins arguments through ``arg=`` is redundant is makes the 168command-line less readable, especially when the argument itself consist of a 169name and a value, e.g. ``-plugin plugin_name,arg="arg_name=arg_value"``. 170Therefore, the usage of ``arg`` is redundant. Single-word arguments are treated 171as short-form boolean values, and passed to plugins as ``arg_name=on``. 172However, short-form booleans are deprecated and full explicit ``arg_name=on`` 173form is preferred. 174 175 176QEMU Machine Protocol (QMP) commands 177------------------------------------ 178 179``blockdev-open-tray``, ``blockdev-close-tray`` argument ``device`` (since 2.8) 180''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 181 182Use argument ``id`` instead. 183 184``eject`` argument ``device`` (since 2.8) 185''''''''''''''''''''''''''''''''''''''''' 186 187Use argument ``id`` instead. 188 189``blockdev-change-medium`` argument ``device`` (since 2.8) 190'''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 191 192Use argument ``id`` instead. 193 194``block_set_io_throttle`` argument ``device`` (since 2.8) 195''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 196 197Use argument ``id`` instead. 198 199``blockdev-add`` empty string argument ``backing`` (since 2.10) 200''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 201 202Use argument value ``null`` instead. 203 204``block-commit`` arguments ``base`` and ``top`` (since 3.1) 205''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 206 207Use arguments ``base-node`` and ``top-node`` instead. 208 209``nbd-server-add`` and ``nbd-server-remove`` (since 5.2) 210'''''''''''''''''''''''''''''''''''''''''''''''''''''''' 211 212Use the more generic commands ``block-export-add`` and ``block-export-del`` 213instead. As part of this deprecation, where ``nbd-server-add`` used a 214single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``. 215 216System accelerators 217------------------- 218 219MIPS ``Trap-and-Emul`` KVM support (since 6.0) 220'''''''''''''''''''''''''''''''''''''''''''''' 221 222The MIPS ``Trap-and-Emul`` KVM host and guest support has been removed 223from Linux upstream kernel, declare it deprecated. 224 225System emulator CPUS 226-------------------- 227 228``Icelake-Client`` CPU Model (since 5.2) 229'''''''''''''''''''''''''''''''''''''''' 230 231``Icelake-Client`` CPU Models are deprecated. Use ``Icelake-Server`` CPU 232Models instead. 233 234MIPS ``I7200`` CPU Model (since 5.2) 235'''''''''''''''''''''''''''''''''''' 236 237The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated 238(the ISA has never been upstreamed to a compiler toolchain). Therefore 239this CPU is also deprecated. 240 241 242QEMU API (QAPI) events 243---------------------- 244 245``MEM_UNPLUG_ERROR`` (since 6.2) 246'''''''''''''''''''''''''''''''''''''''''''''''''''''''' 247 248Use the more generic event ``DEVICE_UNPLUG_GUEST_ERROR`` instead. 249 250 251System emulator machines 252------------------------ 253 254Aspeed ``swift-bmc`` machine (since 6.1) 255'''''''''''''''''''''''''''''''''''''''' 256 257This machine is deprecated because we have enough AST2500 based OpenPOWER 258machines. It can be easily replaced by the ``witherspoon-bmc`` or the 259``romulus-bmc`` machines. 260 261Backend options 262--------------- 263 264Using non-persistent backing file with pmem=on (since 6.1) 265'''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 266 267This option is used when ``memory-backend-file`` is consumed by emulated NVDIMM 268device. However enabling ``memory-backend-file.pmem`` option, when backing file 269is (a) not DAX capable or (b) not on a filesystem that support direct mapping 270of persistent memory, is not safe and may lead to data loss or corruption in case 271of host crash. 272Options are: 273 274 - modify VM configuration to set ``pmem=off`` to continue using fake NVDIMM 275 (without persistence guaranties) with backing file on non DAX storage 276 - move backing file to NVDIMM storage and keep ``pmem=on`` 277 (to have NVDIMM with persistence guaranties). 278 279Device options 280-------------- 281 282Emulated device options 283''''''''''''''''''''''' 284 285``-device virtio-blk,scsi=on|off`` (since 5.0) 286^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 287 288The virtio-blk SCSI passthrough feature is a legacy VIRTIO feature. VIRTIO 1.0 289and later do not support it because the virtio-scsi device was introduced for 290full SCSI support. Use virtio-scsi instead when SCSI passthrough is required. 291 292Note this also applies to ``-device virtio-blk-pci,scsi=on|off``, which is an 293alias. 294 295Block device options 296'''''''''''''''''''' 297 298``"backing": ""`` (since 2.12) 299^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 300 301In order to prevent QEMU from automatically opening an image's backing 302chain, use ``"backing": null`` instead. 303 304``rbd`` keyvalue pair encoded filenames: ``""`` (since 3.1) 305^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 306 307Options for ``rbd`` should be specified according to its runtime options, 308like other block drivers. Legacy parsing of keyvalue pair encoded 309filenames is useful to open images with the old format for backing files; 310These image files should be updated to use the current format. 311 312Example of legacy encoding:: 313 314 json:{"file.driver":"rbd", "file.filename":"rbd:rbd/name"} 315 316The above, converted to the current supported format:: 317 318 json:{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"} 319 320linux-user mode CPUs 321-------------------- 322 323``ppc64abi32`` CPUs (since 5.2) 324''''''''''''''''''''''''''''''' 325 326The ``ppc64abi32`` architecture has a number of issues which regularly 327trip up our CI testing and is suspected to be quite broken. For that 328reason the maintainers strongly suspect no one actually uses it. 329 330MIPS ``I7200`` CPU (since 5.2) 331'''''''''''''''''''''''''''''' 332 333The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated 334(the ISA has never been upstreamed to a compiler toolchain). Therefore 335this CPU is also deprecated. 336 337Related binaries 338---------------- 339 340Backwards compatibility 341----------------------- 342 343Runnability guarantee of CPU models (since 4.1) 344''''''''''''''''''''''''''''''''''''''''''''''' 345 346Previous versions of QEMU never changed existing CPU models in 347ways that introduced additional host software or hardware 348requirements to the VM. This allowed management software to 349safely change the machine type of an existing VM without 350introducing new requirements ("runnability guarantee"). This 351prevented CPU models from being updated to include CPU 352vulnerability mitigations, leaving guests vulnerable in the 353default configuration. 354 355The CPU model runnability guarantee won't apply anymore to 356existing CPU models. Management software that needs runnability 357guarantees must resolve the CPU model aliases using the 358``alias-of`` field returned by the ``query-cpu-definitions`` QMP 359command. 360 361While those guarantees are kept, the return value of 362``query-cpu-definitions`` will have existing CPU model aliases 363point to a version that doesn't break runnability guarantees 364(specifically, version 1 of those CPU models). In future QEMU 365versions, aliases will point to newer CPU model versions 366depending on the machine type, so management software must 367resolve CPU model aliases before starting a virtual machine. 368 369Guest Emulator ISAs 370------------------- 371 372nanoMIPS ISA 373'''''''''''' 374 375The ``nanoMIPS`` ISA has never been upstreamed to any compiler toolchain. 376As it is hard to generate binaries for it, declare it deprecated. 377