| @node Deprecated features |
| @appendix 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 appendix. The feature will remain functional |
| for 2 releases prior to actual removal. 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. |
| |
| @section System emulator command line arguments |
| |
| @subsection -machine enforce-config-section=on|off (since 3.1) |
| |
| The @option{enforce-config-section} parameter is replaced by the |
| @option{-global migration.send-configuration=@var{on|off}} option. |
| |
| @subsection -no-kvm (since 1.3.0) |
| |
| The ``-no-kvm'' argument is now a synonym for setting ``-accel tcg''. |
| |
| @subsection -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. |
| |
| @subsection -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. |
| |
| @subsection -net ...,name=@var{name} (since 3.1) |
| |
| The @option{name} parameter of the @option{-net} option is a synonym |
| for the @option{id} parameter, which should now be used instead. |
| |
| @subsection -smp (invalid topologies) (since 3.1) |
| |
| CPU topology properties should describe whole machine topology including |
| possible CPUs. |
| |
| However, historically it was possible to start QEMU with an incorrect topology |
| where @math{@var{n} <= @var{sockets} * @var{cores} * @var{threads} < @var{maxcpus}}, |
| which could lead to an incorrect topology enumeration by the guest. |
| Support for invalid topologies will be removed, the user must ensure |
| topologies described with -smp include all possible cpus, i.e. |
| @math{@var{sockets} * @var{cores} * @var{threads} = @var{maxcpus}}. |
| |
| @subsection -vnc acl (since 4.0.0) |
| |
| The @code{acl} option to the @code{-vnc} argument has been replaced |
| by the @code{tls-authz} and @code{sasl-authz} options. |
| |
| @subsection 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. |
| |
| @subsection 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 @code{audiodev=} property. Additionally, when using |
| vnc, you should specify an @code{audiodev=} propery if you plan to |
| transmit audio through the VNC protocol. |
| |
| @subsection -mon ...,control=readline,pretty=on|off (since 4.1) |
| |
| The @code{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. |
| |
| @subsection -realtime (since 4.1) |
| |
| The @code{-realtime mlock=on|off} argument has been replaced by the |
| @code{-overcommit mem-lock=on|off} argument. |
| |
| @subsection -numa node,mem=@var{size} (since 4.1) |
| |
| The parameter @option{mem} of @option{-numa node} is used to assign a part of |
| guest RAM to a NUMA node. But when using it, it's impossible to manage specified |
| RAM chunk on the host side (like bind it to a host node, setting bind policy, ...), |
| so guest end-ups 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 @option{memdev}, which does the same as @option{mem} and adds |
| means to actualy manage node RAM on the host side. Use parameter @option{memdev} |
| with @var{memory-backend-ram} backend as an replacement for parameter @option{mem} |
| to achieve the same fake NUMA effect or a properly configured |
| @var{memory-backend-file} backend to actually benefit from NUMA configuration. |
| In future new machine versions will not accept the option but it will still |
| work with old machine types. User can check QAPI schema to see if the legacy |
| option is supported by looking at MachineInfo::numa-mem-supported property. |
| |
| @subsection -numa node (without memory specified) (since 4.1) |
| |
| Splitting RAM by default between NUMA nodes has the same issues as @option{mem} |
| parameter described above with the difference that the role of the user plays |
| QEMU using implicit generic or board specific splitting rule. |
| Use @option{memdev} with @var{memory-backend-ram} backend or @option{mem} (if |
| it's supported by used machine type) to define mapping explictly instead. |
| |
| @subsection -mem-path fallback to RAM (since 4.1) |
| Currently if guest RAM allocation from file pointed by @option{mem-path} |
| fails, QEMU falls back to allocating from RAM, which might result |
| in unpredictable behavior since the backing file specified by the user |
| is ignored. In the future, users will be responsible for making sure |
| the backing storage specified with @option{-mem-path} can actually provide |
| the guest RAM configured with @option{-m} and QEMU will fail to start up if |
| RAM allocation is unsuccessful. |
| |
| @subsection RISC-V -bios (since 4.1) |
| |
| 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 has no changes to the default behaviour to avoid breakages. This |
| default will change in a future QEMU release, so please prepare now. All users |
| of the virt or sifive_u machine must change their command line usage. |
| |
| QEMU 4.1 has three options, please migrate to one of these three: |
| 1. ``-bios none`` - This is the current default behavior if no -bios option |
| is included. QEMU will not automatically load any firmware. It is up |
| to the user to load all the images they need. |
| 2. ``-bios default`` - In a future QEMU release this will become the default |
| behaviour if no -bios option is specified. 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 |
| 3. ``-bios <file>`` - Tells QEMU to load the specified file as the firmwrae. |
| |
| @subsection -tb-size option (since 5.0) |
| |
| QEMU 5.0 introduced an alternative syntax to specify the size of the translation |
| block cache, @option{-accel tcg,tb-size=}. The new syntax deprecates the |
| previously available @option{-tb-size} option. |
| |
| @section QEMU Machine Protocol (QMP) commands |
| |
| @subsection change (since 2.5.0) |
| |
| Use ``blockdev-change-medium'' or ``change-vnc-password'' instead. |
| |
| @subsection migrate_set_downtime and migrate_set_speed (since 2.8.0) |
| |
| Use ``migrate-set-parameters'' instead. |
| |
| @subsection migrate-set-cache-size and query-migrate-cache-size (since 2.11.0) |
| |
| Use ``migrate-set-parameters'' and ``query-migrate-parameters'' instead. |
| |
| @subsection query-block result field dirty-bitmaps[i].status (since 4.0) |
| |
| The ``status'' field of the ``BlockDirtyInfo'' structure, returned by |
| the query-block command is deprecated. Two new boolean fields, |
| ``recording'' and ``busy'' effectively replace it. |
| |
| @subsection 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. |
| |
| @subsection query-cpus (since 2.12.0) |
| |
| The ``query-cpus'' command is replaced by the ``query-cpus-fast'' command. |
| |
| @subsection 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. |
| |
| @subsection cpu-add (since 4.0) |
| |
| Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See |
| documentation of ``query-hotpluggable-cpus'' for additional |
| details. |
| |
| @subsection query-events (since 4.0) |
| |
| The ``query-events'' command has been superseded by the more powerful |
| and accurate ``query-qmp-schema'' command. |
| |
| @subsection 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 |
| |
| @section Human Monitor Protocol (HMP) commands |
| |
| @subsection The hub_id parameter of 'hostfwd_add' / 'hostfwd_remove' (since 3.1) |
| |
| The @option{[hub_id name]} parameter tuple of the 'hostfwd_add' and |
| 'hostfwd_remove' HMP commands has been replaced by @option{netdev_id}. |
| |
| @subsection cpu-add (since 4.0) |
| |
| Use ``device_add'' for hotplugging vCPUs instead of ``cpu-add''. See |
| documentation of ``query-hotpluggable-cpus'' for additional details. |
| |
| @subsection 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. |
| |
| @section Guest Emulator ISAs |
| |
| @subsection RISC-V ISA privledge specification version 1.09.1 (since 4.1) |
| |
| The RISC-V ISA privledge specification version 1.09.1 has been deprecated. |
| 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. |
| |
| @section System emulator CPUS |
| |
| @subsection RISC-V ISA CPUs (since 4.1) |
| |
| The RISC-V cpus with the ISA version in the CPU name have been depcreated. 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. |
| |
| @subsection RISC-V ISA CPUs (since 4.1) |
| |
| The RISC-V no MMU cpus have been depcreated. The two CPUs: ``rv32imacu-nommu`` and |
| ``rv64imacu-nommu`` should no longer be used. Instead the MMU status can be specified |
| via the CPU ``mmu`` option when using the ``rv32`` or ``rv64`` CPUs. |
| |
| @section System emulator devices |
| |
| @subsection 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. |
| |
| @subsection 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. |
| |
| @section System emulator machines |
| |
| @subsection mips r4k platform (since 4.2) |
| |
| This machine type is very old and unmaintained. Users should use the 'malta' |
| machine type instead. |
| |
| @subsection 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. |
| |
| @subsection prep (PowerPC) (since 3.1) |
| |
| This machine type uses an unmaintained firmware, broken in lots of ways, |
| and unable to start post-2004 operating systems. 40p machine type should be |
| used instead. |
| |
| @subsection spike_v1.9.1 and spike_v1.10 (since 4.1) |
| |
| The version specific Spike machines have been deprecated 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=v1.9.1`` command line argument. |
| |
| @section Device options |
| |
| @subsection Block device options |
| |
| @subsubsection "backing": "" (since 2.12.0) |
| |
| In order to prevent QEMU from automatically opening an image's backing |
| chain, use ``"backing": null'' instead. |
| |
| @subsubsection 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: |
| |
| @code{json:@{"file.driver":"rbd", "file.filename":"rbd:rbd/name"@}} |
| |
| The above, converted to the current supported format: |
| |
| @code{json:@{"file.driver":"rbd", "file.pool":"rbd", "file.image":"name"@}} |
| |
| @section Related binaries |
| |
| @subsection qemu-nbd --partition (since 4.0.0) |
| |
| The ``qemu-nbd --partition $digit'' code (also spelled @option{-P}) |
| can only handle MBR partitions, and has never correctly handled |
| logical partitions beyond partition 5. If you know the offset and |
| length of the partition (perhaps by using @code{sfdisk} within the |
| guest), you can achieve the effect of exporting just that subset of |
| the disk by use of the @option{--image-opts} option with a raw |
| blockdev using the @code{offset} and @code{size} parameters layered on |
| top of any other existing blockdev. For example, if partition 1 is |
| 100MiB long starting at 1MiB, the old command: |
| |
| @code{qemu-nbd -t -P 1 -f qcow2 file.qcow2} |
| |
| can be rewritten as: |
| |
| @code{qemu-nbd -t --image-opts driver=raw,offset=1M,size=100M,file.driver=qcow2,file.backing.driver=file,file.backing.filename=file.qcow2} |
| |
| Alternatively, the @code{nbdkit} project provides a more powerful |
| partition filter on top of its nbd plugin, which can be used to select |
| an arbitrary MBR or GPT partition on top of any other full-image NBD |
| export. Using this to rewrite the above example results in: |
| |
| @code{qemu-nbd -t -k /tmp/sock -f qcow2 file.qcow2 &} |
| @code{nbdkit -f --filter=partition nbd socket=/tmp/sock partition=1} |
| |
| Note that if you are exposing the export via /dev/nbd0, it is easier |
| to just export the entire image and then mount only /dev/nbd0p1 than |
| it is to reinvoke @command{qemu-nbd -c /dev/nbd0} limited to just a |
| subset of the image. |
| |
| @subsection qemu-img convert -n -o (since 4.2.0) |
| |
| All options specified in @option{-o} are image creation options, so |
| they have no effect when used with @option{-n} to skip image creation. |
| Silently ignored options can be confusing, so this combination of |
| options will be made an error in future versions. |
| |
| @section Build system |
| |
| @subsection Python 2 support (since 4.1.0) |
| |
| In the future, QEMU will require Python 3 to be available at |
| build time. Support for Python 2 in scripts shipped with QEMU |
| is deprecated. |
| |
| @section Backwards compatibility |
| |
| @subsection 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. |
| |
| |
| @node Recently removed features |
| @appendix 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. |
| |
| @section QEMU Machine Protocol (QMP) commands |
| |
| @subsection 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. |