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 14As a special exception to this general timeframe, rather than have an 15indefinite lifetime, versioned machine types are only intended to be 16supported for a period of 6 years, equivalent to 18 QEMU releases. All 17versioned machine types will be automatically marked deprecated after an 18initial 3 years (9 QEMU releases) has passed, and will then be deleted after 19a further 3 year period has passed. It is recommended that a deprecated 20machine type is only used for incoming migrations and restore of saved state, 21for pre-existing VM deployments. They should be scheduled for updating to a 22newer machine type during an appropriate service window. Newly deployed VMs 23should exclusively use a non-deprecated machine type, with use of the most 24recent version highly recommended. Non-versioned machine types follow the 25general feature deprecation policy. 26 27What follows is a list of all features currently marked as 28deprecated. 29 30System emulator command line arguments 31-------------------------------------- 32 33Short-form boolean options (since 6.0) 34'''''''''''''''''''''''''''''''''''''' 35 36Boolean options such as ``share=on``/``share=off`` could be written 37in short form as ``share`` and ``noshare``. This is now deprecated 38and will cause a warning. 39 40``delay`` option for socket character devices (since 6.0) 41''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 42 43The replacement for the ``nodelay`` short-form boolean option is ``nodelay=on`` 44rather than ``delay=off``. 45 46Plugin argument passing through ``arg=<string>`` (since 6.1) 47'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 48 49Passing TCG plugins arguments through ``arg=`` is redundant is makes the 50command-line less readable, especially when the argument itself consist of a 51name and a value, e.g. ``-plugin plugin_name,arg="arg_name=arg_value"``. 52Therefore, the usage of ``arg`` is redundant. Single-word arguments are treated 53as short-form boolean values, and passed to plugins as ``arg_name=on``. 54However, short-form booleans are deprecated and full explicit ``arg_name=on`` 55form is preferred. 56 57``-smp`` (Unsupported "parameter=1" SMP configurations) (since 9.0) 58''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 59 60Specified CPU topology parameters must be supported by the machine. 61 62In the SMP configuration, users should provide the CPU topology parameters that 63are supported by the target machine. 64 65However, historically it was allowed for users to specify the unsupported 66topology parameter as "1", which is meaningless. So support for this kind of 67configurations (e.g. -smp drawers=1,books=1,clusters=1 for x86 PC machine) is 68marked deprecated since 9.0, users have to ensure that all the topology members 69described with -smp are supported by the target machine. 70 71``-old-param`` option for booting Arm kernels via param_struct (since 10.0) 72''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 73 74The ``-old-param`` command line option is specific to Arm targets: 75it is used when directly booting a guest kernel to pass it the 76command line and other information via the old ``param_struct`` ABI, 77rather than the newer ATAGS or DTB mechanisms. This option was only 78ever needed to support ancient kernels on some old board types 79like the ``akita`` or ``terrier``; it has been deprecated in the 80kernel since 2001. None of the board types QEMU supports need 81``param_struct`` support, so this option has been deprecated and will 82be removed in a future QEMU version. 83 84User-mode emulator command line arguments 85----------------------------------------- 86 87``-p`` (since 9.0) 88'''''''''''''''''' 89 90The ``-p`` option pretends to control the host page size. However, 91it is not possible to change the host page size, and using the 92option only causes failures. 93 94QEMU Machine Protocol (QMP) commands 95------------------------------------ 96 97``blockdev-open-tray``, ``blockdev-close-tray`` argument ``device`` (since 2.8) 98''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 99 100Use argument ``id`` instead. 101 102``eject`` argument ``device`` (since 2.8) 103''''''''''''''''''''''''''''''''''''''''' 104 105Use argument ``id`` instead. 106 107``blockdev-change-medium`` argument ``device`` (since 2.8) 108'''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 109 110Use argument ``id`` instead. 111 112``block_set_io_throttle`` argument ``device`` (since 2.8) 113''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 114 115Use argument ``id`` instead. 116 117``blockdev-add`` empty string argument ``backing`` (since 2.10) 118''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 119 120Use argument value ``null`` instead. 121 122``block-commit`` arguments ``base`` and ``top`` (since 3.1) 123''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 124 125Use arguments ``base-node`` and ``top-node`` instead. 126 127``nbd-server-add`` and ``nbd-server-remove`` (since 5.2) 128'''''''''''''''''''''''''''''''''''''''''''''''''''''''' 129 130Use the more generic commands ``block-export-add`` and ``block-export-del`` 131instead. As part of this deprecation, where ``nbd-server-add`` used a 132single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``. 133 134``query-qmp-schema`` return value member ``values`` (since 6.2) 135''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 136 137Member ``values`` in return value elements with meta-type ``enum`` is 138deprecated. Use ``members`` instead. 139 140``drive-backup`` (since 6.2) 141'''''''''''''''''''''''''''' 142 143Use ``blockdev-backup`` in combination with ``blockdev-add`` instead. 144This change primarily separates the creation/opening process of the backup 145target with explicit, separate steps. ``blockdev-backup`` uses mostly the 146same arguments as ``drive-backup``, except the ``format`` and ``mode`` 147options are removed in favor of using explicit ``blockdev-create`` and 148``blockdev-add`` calls. See :doc:`/interop/live-block-operations` for 149details. 150 151``query-migrationthreads`` (since 9.2) 152'''''''''''''''''''''''''''''''''''''' 153 154To be removed with no replacement, as it reports only a limited set of 155threads (for example, it only reports source side of multifd threads, 156without reporting any destination threads, or non-multifd source threads). 157For debugging purpose, please use ``-name $VM,debug-threads=on`` instead. 158 159``block-job-pause`` (since 10.1) 160'''''''''''''''''''''''''''''''' 161 162Use ``job-pause`` instead. The only difference is that ``job-pause`` 163always reports GenericError on failure when ``block-job-pause`` reports 164DeviceNotActive when block-job is not found. 165 166``block-job-resume`` (since 10.1) 167''''''''''''''''''''''''''''''''' 168 169Use ``job-resume`` instead. The only difference is that ``job-resume`` 170always reports GenericError on failure when ``block-job-resume`` reports 171DeviceNotActive when block-job is not found. 172 173``block-job-complete`` (since 10.1) 174''''''''''''''''''''''''''''''''''' 175 176Use ``job-complete`` instead. The only difference is that ``job-complete`` 177always reports GenericError on failure when ``block-job-complete`` reports 178DeviceNotActive when block-job is not found. 179 180``block-job-dismiss`` (since 10.1) 181'''''''''''''''''''''''''''''''''' 182 183Use ``job-dismiss`` instead. 184 185``block-job-finalize`` (since 10.1) 186''''''''''''''''''''''''''''''''''' 187 188Use ``job-finalize`` instead. 189 190``migrate`` argument ``detach`` (since 10.1) 191'''''''''''''''''''''''''''''''''''''''''''' 192 193This argument has always been ignored. 194 195Host Architectures 196------------------ 197 198Big endian MIPS since 7.2; 32-bit little endian MIPS since 9.2 199'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 200 201As Debian 10 ("Buster") moved into LTS the big endian 32 bit version of 202MIPS moved out of support making it hard to maintain our 203cross-compilation CI tests of the architecture. As we no longer have 204CI coverage support may bitrot away before the deprecation process 205completes. 206 207Likewise, the little endian variant of 32 bit MIPS is not supported by 208Debian 13 ("Trixie") and newer. 209 21064 bit little endian MIPS is still a supported host architecture. 211 212System emulation on 32-bit x86 hosts (since 8.0) 213'''''''''''''''''''''''''''''''''''''''''''''''' 214 215Support for 32-bit x86 host deployments is increasingly uncommon in mainstream 216OS distributions given the widespread availability of 64-bit x86 hardware. 217The QEMU project no longer considers 32-bit x86 support for system emulation to 218be an effective use of its limited resources, and thus intends to discontinue 219it. Since all recent x86 hardware from the past >10 years is capable of the 22064-bit x86 extensions, a corresponding 64-bit OS should be used instead. 221 222TCG Plugin support not enabled by default on 32-bit hosts (since 9.2) 223''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 224 225While it is still possible to enable TCG plugin support for 32-bit 226hosts there are a number of potential pitfalls when instrumenting 22764-bit guests. The plugin APIs typically pass most addresses as 228uint64_t but practices like encoding that address in a host pointer 229for passing as user-data will lose data. As most software analysis 230benefits from having plenty of host memory it seems reasonable to 231encourage users to use 64 bit builds of QEMU for analysis work 232whatever targets they are instrumenting. 233 234TCG Plugin support not enabled by default with TCI (since 9.2) 235'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 236 237While the TCG interpreter can interpret the TCG ops used by plugins it 238is going to be so much slower it wouldn't make sense for any serious 239instrumentation. Due to implementation differences there will also be 240anomalies in things like memory instrumentation. 241 24232-bit host operating systems (since 10.0) 243'''''''''''''''''''''''''''''''''''''''''' 244 245Keeping 32-bit host support alive is a substantial burden for the 246QEMU project. Thus QEMU will in future drop the support for all 24732-bit host systems. 248 249linux-user mode CPUs 250-------------------- 251 252iwMMXt emulation and the ``pxa`` CPUs (since 10.0) 253'''''''''''''''''''''''''''''''''''''''''''''''''' 254 255The ``pxa`` CPU family (``pxa250``, ``pxa255``, ``pxa260``, 256``pxa261``, ``pxa262``, ``pxa270-a0``, ``pxa270-a1``, ``pxa270``, 257``pxa270-b0``, ``pxa270-b1``, ``pxa270-c0``, ``pxa270-c5``) are no 258longer used in system emulation, because all the machine types which 259used these CPUs were removed in the QEMU 9.2 release. These CPUs can 260now only be used in linux-user mode, and to do that you would have to 261explicitly select one of these CPUs with the ``-cpu`` command line 262option or the ``QEMU_CPU`` environment variable. 263 264We don't believe that anybody is using the iwMMXt emulation, and we do 265not have any tests to validate it or any real hardware or similar 266known-good implementation to test against. GCC is in the process of 267dropping their support for iwMMXt codegen. These CPU types are 268therefore deprecated in QEMU, and will be removed in a future release. 269 270System emulator CPUs 271-------------------- 272 273``power5+`` and ``power7+`` CPU names (since 9.0) 274''''''''''''''''''''''''''''''''''''''''''''''''' 275 276The character "+" in device (and thus also CPU) names is not allowed 277in the QEMU object model anymore. ``power5+``, ``power5+_v2.1``, 278``power7+`` and ``power7+_v2.1`` are currently still supported via 279an alias, but for consistency these will get removed in a future 280release, too. Use ``power5p_v2.1`` and ``power7p_v2.1`` instead. 281 282``Sun-UltraSparc-IIIi+`` and ``Sun-UltraSparc-IV+`` CPU names (since 9.1) 283''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 284 285The character "+" in device (and thus also CPU) names is not allowed 286in the QEMU object model anymore. ``Sun-UltraSparc-IIIi+`` and 287``Sun-UltraSparc-IV+`` are currently still supported via a workaround, 288but for consistency these will get removed in a future release, too. 289Use ``Sun-UltraSparc-IIIi-plus`` and ``Sun-UltraSparc-IV-plus`` instead. 290 291PPC 405 CPUs (since 10.0) 292''''''''''''''''''''''''' 293 294The PPC 405 CPU has no known users and the ``ref405ep`` machine was 295removed in QEMU 10.0. Since the IBM POWER [8-11] processors uses an 296embedded 405 for power management (OCC) and other internal tasks, it 297is theoretically possible to use QEMU to model them. Let's keep the 298CPU implementation for a while before removing all support. 299 300System emulator machines 301------------------------ 302 303Versioned machine types (aarch64, arm, i386, m68k, ppc64, s390x, x86_64) 304'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 305 306In accordance with our versioned machine type deprecation policy, all machine 307types with version |VER_MACHINE_DEPRECATION_VERSION|, or older, have been 308deprecated. 309 310Arm ``virt`` machine ``dtb-kaslr-seed`` property (since 7.1) 311'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 312 313The ``dtb-kaslr-seed`` property on the ``virt`` board has been 314deprecated; use the new name ``dtb-randomness`` instead. The new name 315better reflects the way this property affects all random data within 316the device tree blob, not just the ``kaslr-seed`` node. 317 318Mips ``mipssim`` machine (since 10.0) 319''''''''''''''''''''''''''''''''''''' 320 321Linux dropped support for this virtual machine type in kernel v3.7, and 322there does not seem to be anybody around who is still using this board 323in QEMU: Most former MIPS-related people are working on other architectures 324in their everyday job nowadays, and we are also not aware of anybody still 325using old binaries with this board (i.e. there is also no binary available 326online to check that this board did not completely bitrot yet). It is 327recommended to use another MIPS machine for future MIPS code development 328instead. 329 330RISC-V default machine option (since 10.0) 331'''''''''''''''''''''''''''''''''''''''''' 332 333RISC-V defines ``spike`` as the default machine if no machine option is 334given in the command line. This happens because ``spike`` is the first 335RISC-V machine implemented in QEMU and setting it as default was 336convenient at that time. Now we have 7 riscv64 and 6 riscv32 machines 337and having ``spike`` as a default is no longer justified. This default 338will also promote situations where users think they're running ``virt`` 339(the most used RISC-V machine type in 10.0) when in fact they're 340running ``spike``. 341 342Removing the default machine option forces users to always set the machine 343they want to use and avoids confusion. Existing users of the ``spike`` 344machine must ensure that they're setting the ``spike`` machine in the 345command line (``-M spike``). 346 347 348System emulator binaries 349------------------------ 350 351``qemu-system-microblazeel`` (since 10.1) 352''''''''''''''''''''''''''''''''''''''''' 353 354The ``qemu-system-microblaze`` binary can emulate little-endian machines 355now, too, so the separate binary ``qemu-system-microblazeel`` (with the 356``el`` suffix) for little-endian targets is not required anymore. The 357``petalogix-s3adsp1800`` machine can now be switched to little endian by 358setting its ``endianness`` property to ``little``. 359 360 361Backend options 362--------------- 363 364Using non-persistent backing file with pmem=on (since 6.1) 365'''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 366 367This option is used when ``memory-backend-file`` is consumed by emulated NVDIMM 368device. However enabling ``memory-backend-file.pmem`` option, when backing file 369is (a) not DAX capable or (b) not on a filesystem that support direct mapping 370of persistent memory, is not safe and may lead to data loss or corruption in case 371of host crash. 372Options are: 373 374 - modify VM configuration to set ``pmem=off`` to continue using fake NVDIMM 375 (without persistence guaranties) with backing file on non DAX storage 376 - move backing file to NVDIMM storage and keep ``pmem=on`` 377 (to have NVDIMM with persistence guaranties). 378 379Device options 380-------------- 381 382Emulated device options 383''''''''''''''''''''''' 384 385``-device nvme-ns,eui64-default=on|off`` (since 7.1) 386^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 387 388In QEMU versions 6.1, 6.2 and 7.0, the ``nvme-ns`` generates an EUI-64 389identifier that is not globally unique. If an EUI-64 identifier is required, the 390user must set it explicitly using the ``nvme-ns`` device parameter ``eui64``. 391 392``-device nvme,use-intel-id=on|off`` (since 7.1) 393^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 394 395The ``nvme`` device originally used a PCI Vendor/Device Identifier combination 396from Intel that was not properly allocated. Since version 5.2, the controller 397has used a properly allocated identifier. Deprecate the ``use-intel-id`` 398machine compatibility parameter. 399 400``-device cxl-type3,memdev=xxxx`` (since 8.0) 401^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 402 403The ``cxl-type3`` device initially only used a single memory backend. With 404the addition of volatile memory support, it is now necessary to distinguish 405between persistent and volatile memory backends. As such, memdev is deprecated 406in favor of persistent-memdev. 407 408 409RISC-V CPU properties which start with capital 'Z' (since 8.2) 410^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 411 412All RISC-V CPU properties which start with capital 'Z' are being deprecated 413starting in 8.2. The reason is that they were wrongly added with capital 'Z' 414in the past. CPU properties were later added with lower-case names, which 415is the format we want to use from now on. 416 417Users which try to use these deprecated properties will receive a warning 418recommending to switch to their stable counterparts: 419 420- "Zifencei" should be replaced with "zifencei" 421- "Zicsr" should be replaced with "zicsr" 422- "Zihintntl" should be replaced with "zihintntl" 423- "Zihintpause" should be replaced with "zihintpause" 424- "Zawrs" should be replaced with "zawrs" 425- "Zfa" should be replaced with "zfa" 426- "Zfh" should be replaced with "zfh" 427- "Zfhmin" should be replaced with "zfhmin" 428- "Zve32f" should be replaced with "zve32f" 429- "Zve64f" should be replaced with "zve64f" 430- "Zve64d" should be replaced with "zve64d" 431 432``-device sd-card,spec_version=1`` (since 9.1) 433^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 434 435SD physical layer specification v2.00 supersedes the v1.10 one. 436v2.00 is the default since QEMU 3.0.0. 437 438Block device options 439'''''''''''''''''''' 440 441``"backing": ""`` (since 2.12) 442^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 443 444In order to prevent QEMU from automatically opening an image's backing 445chain, use ``"backing": null`` instead. 446 447``rbd`` keyvalue pair encoded filenames: ``""`` (since 3.1) 448^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 449 450Options for ``rbd`` should be specified according to its runtime options, 451like other block drivers. Legacy parsing of keyvalue pair encoded 452filenames is useful to open images with the old format for backing files; 453These image files should be updated to use the current format. 454 455Example of legacy encoding:: 456 457 json:{"file.driver":"rbd", "file.filename":"rbd:rbd/name"} 458 459The above, converted to the current supported format:: 460 461 json:{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"} 462 463``iscsi,password=xxx`` (since 8.0) 464^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 465 466Specifying the iSCSI password in plain text on the command line using the 467``password`` option is insecure. The ``password-secret`` option should be 468used instead, to refer to a ``--object secret...`` instance that provides 469a password via a file, or encrypted. 470 471``gluster`` backend (since 9.2) 472^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 473 474According to https://marc.info/?l=fedora-devel-list&m=171934833215726 475the GlusterFS development effectively ended. Unless the development 476gains momentum again, the QEMU project will remove the gluster backend 477in a future release. 478 479 480Character device options 481'''''''''''''''''''''''' 482 483Backend ``memory`` (since 9.0) 484^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 485 486``memory`` is a deprecated synonym for ``ringbuf``. 487 488``reconnect`` (since 9.2) 489^^^^^^^^^^^^^^^^^^^^^^^^^ 490 491The ``reconnect`` option only allows specifying second granularity timeouts, 492which is not enough for all types of use cases, use ``reconnect-ms`` instead. 493 494 495Net device options 496'''''''''''''''''' 497 498Stream ``reconnect`` (since 9.2) 499^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 500 501The ``reconnect`` option only allows specifying second granularity timeouts, 502which is not enough for all types of use cases, use ``reconnect-ms`` instead. 503 504VFIO device options 505''''''''''''''''''' 506 507``-device vfio-calxeda-xgmac`` (since 10.0) 508^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 509The vfio-calxeda-xgmac device allows to assign a host Calxeda Highbank 51010Gb XGMAC Ethernet controller device ("calxeda,hb-xgmac" compatibility 511string) to a guest. Calxeda HW has been ewasted now and there is no point 512keeping that device. 513 514``-device vfio-amd-xgbe`` (since 10.0) 515^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 516The vfio-amd-xgbe device allows to assign a host AMD 10GbE controller 517to a guest ("amd,xgbe-seattle-v1a" compatibility string). AMD "Seattle" 518is not supported anymore and there is no point keeping that device. 519 520``-device vfio-platform`` (since 10.0) 521^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 522The vfio-platform device allows to assign a host platform device 523to a guest in a generic manner. Integrating a new device into 524the vfio-platform infrastructure requires some adaptation at 525both kernel and qemu level. No such attempt has been done for years 526and the conclusion is that vfio-platform has not got any traction. 527PCIe passthrough shall be the mainline solution. 528 529CPU device properties 530''''''''''''''''''''' 531 532``pmu-num=n`` on RISC-V CPUs (since 8.2) 533^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 534 535In order to support more flexible counter configurations this has been replaced 536by a ``pmu-mask`` property. If set of counters is continuous then the mask can 537be calculated with ``((2 ^ n) - 1) << 3``. The least significant three bits 538must be left clear. 539 540 541``pcommit`` on x86 (since 9.1) 542^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ 543 544The PCOMMIT instruction was never included in any physical processor. 545It was implemented as a no-op instruction in TCG up to QEMU 9.0, but 546only with ``-cpu max`` (which does not guarantee migration compatibility 547across versions). 548 549Backwards compatibility 550----------------------- 551 552Runnability guarantee of CPU models (since 4.1) 553''''''''''''''''''''''''''''''''''''''''''''''' 554 555Previous versions of QEMU never changed existing CPU models in 556ways that introduced additional host software or hardware 557requirements to the VM. This allowed management software to 558safely change the machine type of an existing VM without 559introducing new requirements ("runnability guarantee"). This 560prevented CPU models from being updated to include CPU 561vulnerability mitigations, leaving guests vulnerable in the 562default configuration. 563 564The CPU model runnability guarantee won't apply anymore to 565existing CPU models. Management software that needs runnability 566guarantees must resolve the CPU model aliases using the 567``alias-of`` field returned by the ``query-cpu-definitions`` QMP 568command. 569 570While those guarantees are kept, the return value of 571``query-cpu-definitions`` will have existing CPU model aliases 572point to a version that doesn't break runnability guarantees 573(specifically, version 1 of those CPU models). In future QEMU 574versions, aliases will point to newer CPU model versions 575depending on the machine type, so management software must 576resolve CPU model aliases before starting a virtual machine. 577 578RISC-V "virt" board "riscv,delegate" DT property (since 9.1) 579'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' 580 581The "riscv,delegate" DT property was added in QEMU 7.0 as part of 582the AIA APLIC support. The property changed name during the review 583process in Linux and the correct name ended up being 584"riscv,delegation". Changing the DT property name will break all 585available firmwares that are using the current (wrong) name. The 586property is kept as is in 9.1, together with "riscv,delegation", to 587give more time for firmware developers to change their code. 588 589Migration 590--------- 591 592``fd:`` URI when used for file migration (since 9.1) 593'''''''''''''''''''''''''''''''''''''''''''''''''''' 594 595The ``fd:`` URI can currently provide a file descriptor that 596references either a socket or a plain file. These are two different 597types of migration. In order to reduce ambiguity, the ``fd:`` URI 598usage of providing a file descriptor to a plain file has been 599deprecated in favor of explicitly using the ``file:`` URI with the 600file descriptor being passed as an ``fdset``. Refer to the ``add-fd`` 601command documentation for details on the ``fdset`` usage. 602 603``zero-blocks`` capability (since 9.2) 604'''''''''''''''''''''''''''''''''''''' 605 606The ``zero-blocks`` capability was part of the block migration which 607doesn't exist anymore since it was removed in QEMU v9.1. 608