368 lines
14 KiB
ReStructuredText
368 lines
14 KiB
ReStructuredText
.. _Deprecated features:
|
|
|
|
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.
|
|
|
|
Build options
|
|
-------------
|
|
|
|
``gprof`` builds (since 8.0)
|
|
''''''''''''''''''''''''''''
|
|
|
|
The ``--enable-gprof`` configure setting relies on compiler
|
|
instrumentation to gather its data which can distort the generated
|
|
profile. As other non-instrumenting tools are available that give a
|
|
more holistic view of the system with non-instrumented binaries we are
|
|
deprecating the build option and no longer defend it in CI. The
|
|
``--enable-gcov`` build option remains for analysis test case
|
|
coverage.
|
|
|
|
System emulator command line arguments
|
|
--------------------------------------
|
|
|
|
``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.
|
|
|
|
Short-form boolean options (since 6.0)
|
|
''''''''''''''''''''''''''''''''''''''
|
|
|
|
Boolean options such as ``share=on``/``share=off`` could be written
|
|
in short form as ``share`` and ``noshare``. This is now deprecated
|
|
and will cause a warning.
|
|
|
|
``delay`` option for socket character devices (since 6.0)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
The replacement for the ``nodelay`` short-form boolean option is ``nodelay=on``
|
|
rather than ``delay=off``.
|
|
|
|
``-spice password=string`` (since 6.0)
|
|
''''''''''''''''''''''''''''''''''''''
|
|
|
|
This option is insecure because the SPICE password remains visible in
|
|
the process listing. This is replaced by the new ``password-secret``
|
|
option which lets the password be securely provided on the command
|
|
line using a ``secret`` object instance.
|
|
|
|
``-smp`` ("parameter=0" SMP configurations) (since 6.2)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Specified CPU topology parameters must be greater than zero.
|
|
|
|
In the SMP configuration, users should either provide a CPU topology
|
|
parameter with a reasonable value (greater than zero) or just omit it
|
|
and QEMU will compute the missing value.
|
|
|
|
However, historically it was implicitly allowed for users to provide
|
|
a parameter with zero value, which is meaningless and could also possibly
|
|
cause unexpected results in the -smp parsing. So support for this kind of
|
|
configurations (e.g. -smp 8,sockets=0) is deprecated since 6.2 and will
|
|
be removed in the near future, users have to ensure that all the topology
|
|
members described with -smp are greater than zero.
|
|
|
|
Plugin argument passing through ``arg=<string>`` (since 6.1)
|
|
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Passing TCG plugins arguments through ``arg=`` is redundant is makes the
|
|
command-line less readable, especially when the argument itself consist of a
|
|
name and a value, e.g. ``-plugin plugin_name,arg="arg_name=arg_value"``.
|
|
Therefore, the usage of ``arg`` is redundant. Single-word arguments are treated
|
|
as short-form boolean values, and passed to plugins as ``arg_name=on``.
|
|
However, short-form booleans are deprecated and full explicit ``arg_name=on``
|
|
form is preferred.
|
|
|
|
``-no-hpet`` (since 8.0)
|
|
''''''''''''''''''''''''
|
|
|
|
The HPET setting has been turned into a machine property.
|
|
Use ``-machine hpet=off`` instead.
|
|
|
|
``-accel hax`` (since 8.0)
|
|
''''''''''''''''''''''''''
|
|
|
|
The HAXM project has been retired (see https://github.com/intel/haxm#status).
|
|
Use "whpx" (on Windows) or "hvf" (on macOS) instead.
|
|
|
|
|
|
QEMU Machine Protocol (QMP) commands
|
|
------------------------------------
|
|
|
|
``blockdev-open-tray``, ``blockdev-close-tray`` argument ``device`` (since 2.8)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use argument ``id`` instead.
|
|
|
|
``eject`` argument ``device`` (since 2.8)
|
|
'''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use argument ``id`` instead.
|
|
|
|
``blockdev-change-medium`` argument ``device`` (since 2.8)
|
|
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use argument ``id`` instead.
|
|
|
|
``block_set_io_throttle`` argument ``device`` (since 2.8)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use argument ``id`` instead.
|
|
|
|
``blockdev-add`` empty string argument ``backing`` (since 2.10)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use argument value ``null`` instead.
|
|
|
|
``block-commit`` arguments ``base`` and ``top`` (since 3.1)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use arguments ``base-node`` and ``top-node`` instead.
|
|
|
|
``nbd-server-add`` and ``nbd-server-remove`` (since 5.2)
|
|
''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use the more generic commands ``block-export-add`` and ``block-export-del``
|
|
instead. As part of this deprecation, where ``nbd-server-add`` used a
|
|
single ``bitmap``, the new ``block-export-add`` uses a list of ``bitmaps``.
|
|
|
|
``query-qmp-schema`` return value member ``values`` (since 6.2)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Member ``values`` in return value elements with meta-type ``enum`` is
|
|
deprecated. Use ``members`` instead.
|
|
|
|
``drive-backup`` (since 6.2)
|
|
''''''''''''''''''''''''''''
|
|
|
|
Use ``blockdev-backup`` in combination with ``blockdev-add`` instead.
|
|
This change primarily separates the creation/opening process of the backup
|
|
target with explicit, separate steps. ``blockdev-backup`` uses mostly the
|
|
same arguments as ``drive-backup``, except the ``format`` and ``mode``
|
|
options are removed in favor of using explicit ``blockdev-create`` and
|
|
``blockdev-add`` calls. See :doc:`/interop/live-block-operations` for
|
|
details.
|
|
|
|
Incorrectly typed ``device_add`` arguments (since 6.2)
|
|
''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Due to shortcomings in the internal implementation of ``device_add``, QEMU
|
|
incorrectly accepts certain invalid arguments: Any object or list arguments are
|
|
silently ignored. Other argument types are not checked, but an implicit
|
|
conversion happens, so that e.g. string values can be assigned to integer
|
|
device properties or vice versa.
|
|
|
|
This is a bug in QEMU that will be fixed in the future so that previously
|
|
accepted incorrect commands will return an error. Users should make sure that
|
|
all arguments passed to ``device_add`` are consistent with the documented
|
|
property types.
|
|
|
|
Host Architectures
|
|
------------------
|
|
|
|
BE MIPS (since 7.2)
|
|
'''''''''''''''''''
|
|
|
|
As Debian 10 ("Buster") moved into LTS the big endian 32 bit version of
|
|
MIPS moved out of support making it hard to maintain our
|
|
cross-compilation CI tests of the architecture. As we no longer have
|
|
CI coverage support may bitrot away before the deprecation process
|
|
completes. The little endian variants of MIPS (both 32 and 64 bit) are
|
|
still a supported host architecture.
|
|
|
|
QEMU API (QAPI) events
|
|
----------------------
|
|
|
|
``MEM_UNPLUG_ERROR`` (since 6.2)
|
|
''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
Use the more generic event ``DEVICE_UNPLUG_GUEST_ERROR`` instead.
|
|
|
|
|
|
System emulator machines
|
|
------------------------
|
|
|
|
Arm ``virt`` machine ``dtb-kaslr-seed`` property
|
|
''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
The ``dtb-kaslr-seed`` property on the ``virt`` board has been
|
|
deprecated; use the new name ``dtb-randomness`` instead. The new name
|
|
better reflects the way this property affects all random data within
|
|
the device tree blob, not just the ``kaslr-seed`` node.
|
|
|
|
``pc-i440fx-1.4`` up to ``pc-i440fx-1.7`` (since 7.0)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
These old machine types are quite neglected nowadays and thus might have
|
|
various pitfalls with regards to live migration. Use a newer machine type
|
|
instead.
|
|
|
|
|
|
Backend options
|
|
---------------
|
|
|
|
Using non-persistent backing file with pmem=on (since 6.1)
|
|
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
This option is used when ``memory-backend-file`` is consumed by emulated NVDIMM
|
|
device. However enabling ``memory-backend-file.pmem`` option, when backing file
|
|
is (a) not DAX capable or (b) not on a filesystem that support direct mapping
|
|
of persistent memory, is not safe and may lead to data loss or corruption in case
|
|
of host crash.
|
|
Options are:
|
|
|
|
- modify VM configuration to set ``pmem=off`` to continue using fake NVDIMM
|
|
(without persistence guaranties) with backing file on non DAX storage
|
|
- move backing file to NVDIMM storage and keep ``pmem=on``
|
|
(to have NVDIMM with persistence guaranties).
|
|
|
|
Device options
|
|
--------------
|
|
|
|
Emulated device options
|
|
'''''''''''''''''''''''
|
|
|
|
``-device virtio-blk,scsi=on|off`` (since 5.0)
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
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.
|
|
|
|
``-device nvme-ns,eui64-default=on|off`` (since 7.1)
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
In QEMU versions 6.1, 6.2 and 7.0, the ``nvme-ns`` generates an EUI-64
|
|
identifier that is not globally unique. If an EUI-64 identifier is required, the
|
|
user must set it explicitly using the ``nvme-ns`` device parameter ``eui64``.
|
|
|
|
``-device nvme,use-intel-id=on|off`` (since 7.1)
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
The ``nvme`` device originally used a PCI Vendor/Device Identifier combination
|
|
from Intel that was not properly allocated. Since version 5.2, the controller
|
|
has used a properly allocated identifier. Deprecate the ``use-intel-id``
|
|
machine compatibility parameter.
|
|
|
|
|
|
Block device options
|
|
''''''''''''''''''''
|
|
|
|
``"backing": ""`` (since 2.12)
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
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)
|
|
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
|
|
|
|
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"}
|
|
|
|
Backwards compatibility
|
|
-----------------------
|
|
|
|
Runnability guarantee of CPU models (since 4.1)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
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 the
|
|
``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.
|
|
|
|
Tools
|
|
-----
|
|
|
|
virtiofsd
|
|
'''''''''
|
|
|
|
There is a new Rust implementation of ``virtiofsd`` at
|
|
``https://gitlab.com/virtio-fs/virtiofsd``;
|
|
since this is now marked stable, new development should be done on that
|
|
rather than the existing C version in the QEMU tree.
|
|
The C version will still accept fixes and patches that
|
|
are already in development for the moment, but will eventually
|
|
be deleted from this tree.
|
|
New deployments should use the Rust version, and existing systems
|
|
should consider moving to it. The command line and feature set
|
|
is very close and moving should be simple.
|
|
|
|
|
|
QEMU guest agent
|
|
----------------
|
|
|
|
``--blacklist`` command line option (since 7.2)
|
|
'''''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
``--blacklist`` has been replaced by ``--block-rpcs`` (which is a better
|
|
wording for what this option does). The short form ``-b`` still stays
|
|
the same and thus is the preferred way for scripts that should run with
|
|
both, older and future versions of QEMU.
|
|
|
|
``blacklist`` config file option (since 7.2)
|
|
''''''''''''''''''''''''''''''''''''''''''''
|
|
|
|
The ``blacklist`` config file option has been renamed to ``block-rpcs``
|
|
(to be in sync with the renaming of the corresponding command line
|
|
option).
|