| Deprecated features |
| =================== |
| |
| In general features are intended to be supported indefinitely once |
| introduced into QEMU. In the event that a feature needs to be removed, |
| it will be listed in this section. The feature will remain functional for the |
| release in which it was deprecated and one further release. After these two |
| releases, the feature is liable to be removed. Deprecated features may also |
| generate warnings on the console when QEMU starts up, or if activated via a |
| monitor command, however, this is not a mandatory requirement. |
| |
| Prior to the 2.10.0 release there was no official policy on how |
| long features would be deprecated prior to their removal, nor |
| any documented list of which features were deprecated. Thus |
| any features deprecated prior to 2.10.0 will be treated as if |
| they were first deprecated in the 2.10.0 release. |
| |
| What follows is a list of all features currently marked as |
| deprecated. |
| |
| System emulator command line arguments |
| -------------------------------------- |
| |
| ``-machine enforce-config-section=on|off`` (since 3.1) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``enforce-config-section`` parameter is replaced by the |
| ``-global migration.send-configuration={on|off}`` option. |
| |
| ``-no-kvm`` (since 1.3.0) |
| ''''''''''''''''''''''''' |
| |
| The ``-no-kvm`` argument is now a synonym for setting ``-accel tcg``. |
| |
| ``-usbdevice`` (since 2.10.0) |
| ''''''''''''''''''''''''''''' |
| |
| The ``-usbdevice DEV`` argument is now a synonym for setting |
| the ``-device usb-DEV`` argument instead. The deprecated syntax |
| would automatically enable USB support on the machine type. |
| If using the new syntax, USB support must be explicitly |
| enabled via the ``-machine usb=on`` argument. |
| |
| ``-drive file=json:{...{'driver':'file'}}`` (since 3.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The 'file' driver for drives is no longer appropriate for character or host |
| devices and will only accept regular files (S_IFREG). The correct driver |
| for these file types is 'host_cdrom' or 'host_device' as appropriate. |
| |
| ``-vnc acl`` (since 4.0.0) |
| '''''''''''''''''''''''''' |
| |
| The ``acl`` option to the ``-vnc`` argument has been replaced |
| by the ``tls-authz`` and ``sasl-authz`` options. |
| |
| ``QEMU_AUDIO_`` environment variables and ``-audio-help`` (since 4.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``-audiodev`` argument is now the preferred way to specify audio |
| backend settings instead of environment variables. To ease migration to |
| the new format, the ``-audiodev-help`` option can be used to convert |
| the current values of the environment variables to ``-audiodev`` options. |
| |
| Creating sound card devices and vnc without ``audiodev=`` property (since 4.2) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| When not using the deprecated legacy audio config, each sound card |
| should specify an ``audiodev=`` property. Additionally, when using |
| vnc, you should specify an ``audiodev=`` property if you plan to |
| transmit audio through the VNC protocol. |
| |
| Creating sound card devices using ``-soundhw`` (since 5.1) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Sound card devices should be created using ``-device`` instead. The |
| names are the same for most devices. The exceptions are ``hda`` which |
| needs two devices (``-device intel-hda -device hda-duplex``) and |
| ``pcspk`` which can be activated using ``-machine |
| pcspk-audiodev=<name>``. |
| |
| ``-mon ...,control=readline,pretty=on|off`` (since 4.1) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``pretty=on|off`` switch has no effect for HMP monitors, but is |
| silently ignored. Using the switch with HMP monitors will become an |
| error in the future. |
| |
| ``-realtime`` (since 4.1) |
| ''''''''''''''''''''''''' |
| |
| The ``-realtime mlock=on|off`` argument has been replaced by the |
| ``-overcommit mem-lock=on|off`` argument. |
| |
| RISC-V ``-bios`` (since 5.1) |
| '''''''''''''''''''''''''''' |
| |
| QEMU 4.1 introduced support for the -bios option in QEMU for RISC-V for the |
| RISC-V virt machine and sifive_u machine. QEMU 4.1 had no changes to the |
| default behaviour to avoid breakages. |
| |
| QEMU 5.1 changes the default behaviour from ``-bios none`` to ``-bios default``. |
| |
| QEMU 5.1 has three options: |
| 1. ``-bios default`` - This is the current default behavior if no -bios option |
| is included. This option will load the default OpenSBI firmware automatically. |
| The firmware is included with the QEMU release and no user interaction is |
| required. All a user needs to do is specify the kernel they want to boot |
| with the -kernel option |
| 2. ``-bios none`` - QEMU will not automatically load any firmware. It is up |
| to the user to load all the images they need. |
| 3. ``-bios <file>`` - Tells QEMU to load the specified file as the firmwrae. |
| |
| ``-tb-size`` option (since 5.0) |
| ''''''''''''''''''''''''''''''' |
| |
| QEMU 5.0 introduced an alternative syntax to specify the size of the translation |
| block cache, ``-accel tcg,tb-size=``. The new syntax deprecates the |
| previously available ``-tb-size`` option. |
| |
| ``-show-cursor`` option (since 5.0) |
| ''''''''''''''''''''''''''''''''''' |
| |
| Use ``-display sdl,show-cursor=on`` or |
| ``-display gtk,show-cursor=on`` instead. |
| |
| ``Configuring floppies with ``-global`` |
| ''''''''''''''''''''''''''''''''''''''' |
| |
| Use ``-device floppy,...`` instead: |
| :: |
| |
| -global isa-fdc.driveA=... |
| -global sysbus-fdc.driveA=... |
| -global SUNW,fdtwo.drive=... |
| |
| become |
| :: |
| |
| -device floppy,unit=0,drive=... |
| |
| and |
| :: |
| |
| -global isa-fdc.driveB=... |
| -global sysbus-fdc.driveB=... |
| |
| become |
| :: |
| |
| -device floppy,unit=1,drive=... |
| |
| ``-drive`` with bogus interface type |
| '''''''''''''''''''''''''''''''''''' |
| |
| Drives with interface types other than ``if=none`` are for onboard |
| devices. It is possible to use drives the board doesn't pick up with |
| -device. This usage is now deprecated. Use ``if=none`` instead. |
| |
| |
| QEMU Machine Protocol (QMP) commands |
| ------------------------------------ |
| |
| ``change`` (since 2.5.0) |
| '''''''''''''''''''''''' |
| |
| Use ``blockdev-change-medium`` or ``change-vnc-password`` instead. |
| |
| ``blockdev-open-tray``, ``blockdev-close-tray`` argument ``device`` (since 2.8.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use argument ``id`` instead. |
| |
| ``eject`` argument ``device`` (since 2.8.0) |
| ''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use argument ``id`` instead. |
| |
| ``blockdev-change-medium`` argument ``device`` (since 2.8.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use argument ``id`` instead. |
| |
| ``block_set_io_throttle`` argument ``device`` (since 2.8.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use argument ``id`` instead. |
| |
| ``migrate_set_downtime`` and ``migrate_set_speed`` (since 2.8.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use ``migrate-set-parameters`` instead. |
| |
| ``query-named-block-nodes`` result ``encryption_key_missing`` (since 2.10.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Always false. |
| |
| ``query-block`` result ``inserted.encryption_key_missing`` (since 2.10.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Always false. |
| |
| ``blockdev-add`` empty string argument ``backing`` (since 2.10.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use argument value ``null`` instead. |
| |
| ``migrate-set-cache-size`` and ``query-migrate-cache-size`` (since 2.11.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use ``migrate-set-parameters`` and ``query-migrate-parameters`` instead. |
| |
| ``block-commit`` arguments ``base`` and ``top`` (since 3.1.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use arguments ``base-node`` and ``top-node`` instead. |
| |
| ``object-add`` option ``props`` (since 5.0) |
| ''''''''''''''''''''''''''''''''''''''''''' |
| |
| Specify the properties for the object as top-level arguments instead. |
| |
| ``query-named-block-nodes`` and ``query-block`` result dirty-bitmaps[i].status (since 4.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``status`` field of the ``BlockDirtyInfo`` structure, returned by |
| these commands is deprecated. Two new boolean fields, ``recording`` and |
| ``busy`` effectively replace it. |
| |
| ``query-block`` result field ``dirty-bitmaps`` (Since 4.2) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by |
| the query-block command is itself now deprecated. The ``dirty-bitmaps`` |
| field of the ``BlockDeviceInfo`` struct should be used instead, which is the |
| type of the ``inserted`` field in query-block replies, as well as the |
| type of array items in query-named-block-nodes. |
| |
| Since the ``dirty-bitmaps`` field is optionally present in both the old and |
| new locations, clients must use introspection to learn where to anticipate |
| the field if/when it does appear in command output. |
| |
| ``query-cpus`` (since 2.12.0) |
| ''''''''''''''''''''''''''''' |
| |
| The ``query-cpus`` command is replaced by the ``query-cpus-fast`` command. |
| |
| ``query-cpus-fast`` ``arch`` output member (since 3.0.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``arch`` output member of the ``query-cpus-fast`` command is |
| replaced by the ``target`` output member. |
| |
| ``query-events`` (since 4.0) |
| '''''''''''''''''''''''''''' |
| |
| The ``query-events`` command has been superseded by the more powerful |
| and accurate ``query-qmp-schema`` command. |
| |
| chardev client socket with ``wait`` option (since 4.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Character devices creating sockets in client mode should not specify |
| the 'wait' field, which is only applicable to sockets in server mode |
| |
| ``nbd-server-add`` and ``nbd-server-remove`` (since 5.2) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Use the more generic commands ``block-export-add`` and ``block-export-del`` |
| instead. |
| |
| Human Monitor Protocol (HMP) commands |
| ------------------------------------- |
| |
| ``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, ``acl_remove`` (since 4.0.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, and |
| ``acl_remove`` commands are deprecated with no replacement. Authorization |
| for VNC should be performed using the pluggable QAuthZ objects. |
| |
| System emulator CPUS |
| -------------------- |
| |
| ``moxie`` CPU (since 5.2.0) |
| ''''''''''''''''''''''''''' |
| |
| The ``moxie`` guest CPU support is deprecated and will be removed in |
| a future version of QEMU. It's unclear whether anybody is still using |
| CPU emulation in QEMU, and there are no test images available to make |
| sure that the code is still working. |
| |
| ``compat`` property of server class POWER CPUs (since 5.0) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``compat`` property used to set backwards compatibility modes for |
| the processor has been deprecated. The ``max-cpu-compat`` property of |
| the ``pseries`` machine type should be used instead. |
| |
| ``lm32`` CPUs (since 5.2.0) |
| ''''''''''''''''''''''''''' |
| |
| The ``lm32`` guest CPU support is deprecated and will be removed in |
| a future version of QEMU. The only public user of this architecture |
| was the milkymist project, which has been dead for years; there was |
| never an upstream Linux port. |
| |
| ``unicore32`` CPUs (since 5.2.0) |
| '''''''''''''''''''''''''''''''' |
| |
| The ``unicore32`` guest CPU support is deprecated and will be removed in |
| a future version of QEMU. Support for this CPU was removed from the |
| upstream Linux kernel, and there is no available upstream toolchain |
| to build binaries for it. |
| |
| System emulator devices |
| ----------------------- |
| |
| ``ide-drive`` (since 4.2) |
| ''''''''''''''''''''''''' |
| |
| The 'ide-drive' device is deprecated. Users should use 'ide-hd' or |
| 'ide-cd' as appropriate to get an IDE hard disk or CD-ROM as needed. |
| |
| ``scsi-disk`` (since 4.2) |
| ''''''''''''''''''''''''' |
| |
| The 'scsi-disk' device is deprecated. Users should use 'scsi-hd' or |
| 'scsi-cd' as appropriate to get a SCSI hard disk or CD-ROM as needed. |
| |
| System emulator machines |
| ------------------------ |
| |
| mips ``r4k`` platform (since 5.0) |
| ''''''''''''''''''''''''''''''''' |
| |
| This machine type is very old and unmaintained. Users should use the ``malta`` |
| machine type instead. |
| |
| mips ``fulong2e`` machine (since 5.1) |
| ''''''''''''''''''''''''''''''''''''' |
| |
| This machine has been renamed ``fuloong2e``. |
| |
| ``pc-1.0``, ``pc-1.1``, ``pc-1.2`` and ``pc-1.3`` (since 5.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| These machine types are very old and likely can not be used for live migration |
| from old QEMU versions anymore. A newer machine type should be used instead. |
| |
| Device options |
| -------------- |
| |
| Emulated device options |
| ''''''''''''''''''''''' |
| |
| ``-device virtio-blk,scsi=on|off`` (since 5.0.0) |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| The virtio-blk SCSI passthrough feature is a legacy VIRTIO feature. VIRTIO 1.0 |
| and later do not support it because the virtio-scsi device was introduced for |
| full SCSI support. Use virtio-scsi instead when SCSI passthrough is required. |
| |
| Note this also applies to ``-device virtio-blk-pci,scsi=on|off``, which is an |
| alias. |
| |
| Block device options |
| '''''''''''''''''''' |
| |
| ``"backing": ""`` (since 2.12.0) |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| In order to prevent QEMU from automatically opening an image's backing |
| chain, use ``"backing": null`` instead. |
| |
| ``rbd`` keyvalue pair encoded filenames: ``""`` (since 3.1.0) |
| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ |
| |
| Options for ``rbd`` should be specified according to its runtime options, |
| like other block drivers. Legacy parsing of keyvalue pair encoded |
| filenames is useful to open images with the old format for backing files; |
| These image files should be updated to use the current format. |
| |
| Example of legacy encoding:: |
| |
| json:{"file.driver":"rbd", "file.filename":"rbd:rbd/name"} |
| |
| The above, converted to the current supported format:: |
| |
| json:{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"} |
| |
| linux-user mode CPUs |
| -------------------- |
| |
| ``tilegx`` CPUs (since 5.1.0) |
| ''''''''''''''''''''''''''''' |
| |
| The ``tilegx`` guest CPU support (which was only implemented in |
| linux-user mode) is deprecated and will be removed in a future version |
| of QEMU. Support for this CPU was removed from the upstream Linux |
| kernel in 2018, and has also been dropped from glibc. |
| |
| ``ppc64abi32`` CPUs (since 5.2.0) |
| ''''''''''''''''''''''''''''''''' |
| |
| The ``ppc64abi32`` architecture has a number of issues which regularly |
| trip up our CI testing and is suspected to be quite broken. For that |
| reason the maintainers strongly suspect no one actually uses it. |
| |
| Related binaries |
| ---------------- |
| |
| qemu-img amend to adjust backing file (since 5.1) |
| ''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The use of ``qemu-img amend`` to modify the name or format of a qcow2 |
| backing image is deprecated; this functionality was never fully |
| documented or tested, and interferes with other amend operations that |
| need access to the original backing image (such as deciding whether a |
| v3 zero cluster may be left unallocated when converting to a v2 |
| image). Rather, any changes to the backing chain should be performed |
| with ``qemu-img rebase -u`` either before or after the remaining |
| changes being performed by amend, as appropriate. |
| |
| qemu-img backing file without format (since 5.1) |
| '''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The use of ``qemu-img create``, ``qemu-img rebase``, or ``qemu-img |
| convert`` to create or modify an image that depends on a backing file |
| now recommends that an explicit backing format be provided. This is |
| for safety: if QEMU probes a different format than what you thought, |
| the data presented to the guest will be corrupt; similarly, presenting |
| a raw image to a guest allows a potential security exploit if a future |
| probe sees a non-raw image based on guest writes. |
| |
| To avoid the warning message, or even future refusal to create an |
| unsafe image, you must pass ``-o backing_fmt=`` (or the shorthand |
| ``-F`` during create) to specify the intended backing format. You may |
| use ``qemu-img rebase -u`` to retroactively add a backing format to an |
| existing image. However, be aware that there are already potential |
| security risks to blindly using ``qemu-img info`` to probe the format |
| of an untrusted backing image, when deciding what format to add into |
| an existing image. |
| |
| Backwards compatibility |
| ----------------------- |
| |
| Runnability guarantee of CPU models (since 4.1.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Previous versions of QEMU never changed existing CPU models in |
| ways that introduced additional host software or hardware |
| requirements to the VM. This allowed management software to |
| safely change the machine type of an existing VM without |
| introducing new requirements ("runnability guarantee"). This |
| prevented CPU models from being updated to include CPU |
| vulnerability mitigations, leaving guests vulnerable in the |
| default configuration. |
| |
| The CPU model runnability guarantee won't apply anymore to |
| existing CPU models. Management software that needs runnability |
| guarantees must resolve the CPU model aliases using te |
| ``alias-of`` field returned by the ``query-cpu-definitions`` QMP |
| command. |
| |
| While those guarantees are kept, the return value of |
| ``query-cpu-definitions`` will have existing CPU model aliases |
| point to a version that doesn't break runnability guarantees |
| (specifically, version 1 of those CPU models). In future QEMU |
| versions, aliases will point to newer CPU model versions |
| depending on the machine type, so management software must |
| resolve CPU model aliases before starting a virtual machine. |
| |
| |
| Recently removed features |
| ========================= |
| |
| What follows is a record of recently removed, formerly deprecated |
| features that serves as a record for users who have encountered |
| trouble after a recent upgrade. |
| |
| System emulator command line arguments |
| -------------------------------------- |
| |
| ``-net ...,name=``\ *name* (removed in 5.1) |
| ''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``name`` parameter of the ``-net`` option was a synonym |
| for the ``id`` parameter, which should now be used instead. |
| |
| QEMU Machine Protocol (QMP) commands |
| ------------------------------------ |
| |
| ``block-dirty-bitmap-add`` "autoload" parameter (since 4.2.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The "autoload" parameter has been ignored since 2.12.0. All bitmaps |
| are automatically loaded from qcow2 images. |
| |
| ``cpu-add`` (removed in 5.2) |
| '''''''''''''''''''''''''''' |
| |
| Use ``device_add`` for hotplugging vCPUs instead of ``cpu-add``. See |
| documentation of ``query-hotpluggable-cpus`` for additional details. |
| |
| Human Monitor Protocol (HMP) commands |
| ------------------------------------- |
| |
| The ``hub_id`` parameter of ``hostfwd_add`` / ``hostfwd_remove`` (removed in 5.0) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``[hub_id name]`` parameter tuple of the 'hostfwd_add' and |
| 'hostfwd_remove' HMP commands has been replaced by ``netdev_id``. |
| |
| ``cpu-add`` (removed in 5.2) |
| '''''''''''''''''''''''''''' |
| |
| Use ``device_add`` for hotplugging vCPUs instead of ``cpu-add``. See |
| documentation of ``query-hotpluggable-cpus`` for additional details. |
| |
| Guest Emulator ISAs |
| ------------------- |
| |
| RISC-V ISA privilege specification version 1.09.1 (removed in 5.1) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The RISC-V ISA privilege specification version 1.09.1 has been removed. |
| QEMU supports both the newer version 1.10.0 and the ratified version 1.11.0, these |
| should be used instead of the 1.09.1 version. |
| |
| System emulator CPUS |
| -------------------- |
| |
| KVM guest support on 32-bit Arm hosts (removed in 5.2) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The Linux kernel has dropped support for allowing 32-bit Arm systems |
| to host KVM guests as of the 5.7 kernel. Accordingly, QEMU is deprecating |
| its support for this configuration and will remove it in a future version. |
| Running 32-bit guests on a 64-bit Arm host remains supported. |
| |
| RISC-V ISA Specific CPUs (removed in 5.1) |
| ''''''''''''''''''''''''''''''''''''''''' |
| |
| The RISC-V cpus with the ISA version in the CPU name have been removed. The |
| four CPUs are: ``rv32gcsu-v1.9.1``, ``rv32gcsu-v1.10.0``, ``rv64gcsu-v1.9.1`` and |
| ``rv64gcsu-v1.10.0``. Instead the version can be specified via the CPU ``priv_spec`` |
| option when using the ``rv32`` or ``rv64`` CPUs. |
| |
| RISC-V no MMU CPUs (removed in 5.1) |
| ''''''''''''''''''''''''''''''''''' |
| |
| The RISC-V no MMU cpus have been removed. The two CPUs: ``rv32imacu-nommu`` and |
| ``rv64imacu-nommu`` can no longer be used. Instead the MMU status can be specified |
| via the CPU ``mmu`` option when using the ``rv32`` or ``rv64`` CPUs. |
| |
| System emulator machines |
| ------------------------ |
| |
| ``spike_v1.9.1`` and ``spike_v1.10`` (removed in 5.1) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| The version specific Spike machines have been removed in favour of the |
| generic ``spike`` machine. If you need to specify an older version of the RISC-V |
| spec you can use the ``-cpu rv64gcsu,priv_spec=v1.10.0`` command line argument. |
| |
| Related binaries |
| ---------------- |
| |
| ``qemu-nbd --partition`` (removed in 5.0) |
| ''''''''''''''''''''''''''''''''''''''''' |
| |
| The ``qemu-nbd --partition $digit`` code (also spelled ``-P``) |
| could only handle MBR partitions, and never correctly handled logical |
| partitions beyond partition 5. Exporting a partition can still be |
| done by utilizing the ``--image-opts`` option with a raw blockdev |
| using the ``offset`` and ``size`` parameters layered on top of |
| any other existing blockdev. For example, if partition 1 is 100MiB |
| long starting at 1MiB, the old command:: |
| |
| qemu-nbd -t -P 1 -f qcow2 file.qcow2 |
| |
| can be rewritten as:: |
| |
| qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.file.driver=file,file.file.filename=file.qcow2 |
| |
| ``qemu-img convert -n -o`` (removed in 5.1) |
| ''''''''''''''''''''''''''''''''''''''''''' |
| |
| All options specified in ``-o`` are image creation options, so |
| they are now rejected when used with ``-n`` to skip image creation. |
| |
| |
| ``qemu-img create -b bad file $size`` (removed in 5.1) |
| '''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| When creating an image with a backing file that could not be opened, |
| ``qemu-img create`` used to issue a warning about the failure but |
| proceed with the image creation if an explicit size was provided. |
| However, as the ``-u`` option exists for this purpose, it is safer to |
| enforce that any failure to open the backing image (including if the |
| backing file is missing or an incorrect format was specified) is an |
| error when ``-u`` is not used. |
| |
| Command line options |
| -------------------- |
| |
| ``-smp`` (invalid topologies) (removed 5.2) |
| ''''''''''''''''''''''''''''''''''''''''''' |
| |
| CPU topology properties should describe whole machine topology including |
| possible CPUs. |
| |
| However, historically it was possible to start QEMU with an incorrect topology |
| where *n* <= *sockets* * *cores* * *threads* < *maxcpus*, |
| which could lead to an incorrect topology enumeration by the guest. |
| Support for invalid topologies is removed, the user must ensure |
| topologies described with -smp include all possible cpus, i.e. |
| *sockets* * *cores* * *threads* = *maxcpus*. |
| |
| ``-numa`` node (without memory specified) (removed 5.2) |
| ''''''''''''''''''''''''''''''''''''''''''''''''''''''' |
| |
| Splitting RAM by default between NUMA nodes had the same issues as ``mem`` |
| parameter with the difference that the role of the user plays QEMU using |
| implicit generic or board specific splitting rule. |
| Use ``memdev`` with *memory-backend-ram* backend or ``mem`` (if |
| it's supported by used machine type) to define mapping explictly instead. |
| Users of existing VMs, wishing to preserve the same RAM distribution, should |
| configure it explicitly using ``-numa node,memdev`` options. Current RAM |
| distribution can be retrieved using HMP command ``info numa`` and if separate |
| memory devices (pc|nv-dimm) are present use ``info memory-device`` and subtract |
| device memory from output of ``info numa``. |
| |
| ``-numa node,mem=``\ *size* (removed in 5.1) |
| '''''''''''''''''''''''''''''''''''''''''''' |
| |
| The parameter ``mem`` of ``-numa node`` was used to assign a part of |
| guest RAM to a NUMA node. But when using it, it's impossible to manage a specified |
| RAM chunk on the host side (like bind it to a host node, setting bind policy, ...), |
| so the guest ends up with the fake NUMA configuration with suboptiomal performance. |
| However since 2014 there is an alternative way to assign RAM to a NUMA node |
| using parameter ``memdev``, which does the same as ``mem`` and adds |
| means to actually manage node RAM on the host side. Use parameter ``memdev`` |
| with *memory-backend-ram* backend as replacement for parameter ``mem`` |
| to achieve the same fake NUMA effect or a properly configured |
| *memory-backend-file* backend to actually benefit from NUMA configuration. |
| New machine versions (since 5.1) will not accept the option but it will still |
| work with old machine types. User can check the QAPI schema to see if the legacy |
| option is supported by looking at MachineInfo::numa-mem-supported property. |
| |
| ``-mem-path`` fallback to RAM (removed in 5.0) |
| '''''''''''''''''''''''''''''''''''''''''''''' |
| |
| If guest RAM allocation from file pointed by ``mem-path`` failed, |
| QEMU was falling back to allocating from RAM, which might have resulted |
| in unpredictable behavior since the backing file specified by the user |
| as ignored. Currently, users are responsible for making sure the backing storage |
| specified with ``-mem-path`` can actually provide the guest RAM configured with |
| ``-m`` and QEMU fails to start up if RAM allocation is unsuccessful. |
| |
| ``-smp`` (invalid topologies) (removed 5.2) |
| ''''''''''''''''''''''''''''''''''''''''''' |
| |
| CPU topology properties should describe whole machine topology including |
| possible CPUs. |
| |
| However, historically it was possible to start QEMU with an incorrect topology |
| where *n* <= *sockets* * *cores* * *threads* < *maxcpus*, |
| which could lead to an incorrect topology enumeration by the guest. |
| Support for invalid topologies is removed, the user must ensure |
| topologies described with -smp include all possible cpus, i.e. |
| *sockets* * *cores* * *threads* = *maxcpus*. |
| |
| Block devices |
| ------------- |
| |
| VXHS backend (removed in 5.1) |
| ''''''''''''''''''''''''''''' |
| |
| The VXHS code does not compile since v2.12.0. It was removed in 5.1. |