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docs: Move deprecation, build and license info out of system/

Browse source 
Now that we have a single Sphinx manual rather than multiple manuals,
we can provide a better place for "common to all of QEMU" information
like the deprecation notices, build platforms, license information,
which we currently have in the system/ manual even though it applies
to all of QEMU.

Create a new directory about/ on the same level as system/, user/,
etc, and move these documents there.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Message-id: 20210705095547.15790-5-peter.maydell@linaro.org
This commit is contained in:
Peter Maydell 2021-07-05 10:55:44 +01:00
parent 21b6c26d63
commit f347839258
7 changed files with 11 additions and 4 deletions
Download patch file Download diff file Expand all files Collapse all files

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.. _Supported-build-platforms:
Supported build platforms
=========================
QEMU aims to support building and executing on multiple host OS
platforms. This appendix outlines which platforms are the major build
targets. These platforms are used as the basis for deciding upon the
minimum required versions of 3rd party software QEMU depends on. The
supported platforms are the targets for automated testing performed by
the project when patches are submitted for review, and tested before and
after merge.
If a platform is not listed here, it does not imply that QEMU won't
work. If an unlisted platform has comparable software versions to a
listed platform, there is every expectation that it will work. Bug
reports are welcome for problems encountered on unlisted platforms
unless they are clearly older vintage than what is described here.
Note that when considering software versions shipped in distros as
support targets, QEMU considers only the version number, and assumes the
features in that distro match the upstream release with the same
version. In other words, if a distro backports extra features to the
software in their distro, QEMU upstream code will not add explicit
support for those backports, unless the feature is auto-detectable in a
manner that works for the upstream releases too.
The `Repology`_ site is a useful resource to identify
currently shipped versions of software in various operating systems,
though it does not cover all distros listed below.
Linux OS, macOS, FreeBSD, NetBSD, OpenBSD
-----------------------------------------
The project aims to support the most recent major version at all times. Support
for the previous major version will be dropped 2 years after the new major
version is released or when the vendor itself drops support, whichever comes
first. In this context, third-party efforts to extend the lifetime of a distro
are not considered, even when they are endorsed by the vendor (eg. Debian LTS).
For the purposes of identifying supported software versions available on Linux,
the project will look at CentOS, Debian, Fedora, openSUSE, RHEL, SLES and
Ubuntu LTS. Other distros will be assumed to ship similar software versions.
For FreeBSD and OpenBSD, decisions will be made based on the contents of the
respective ports repository, while NetBSD will use the pkgsrc repository.
For macOS, `HomeBrew`_ will be used, although `MacPorts`_ is expected to carry
similar versions.
Windows
-------
The project supports building with current versions of the MinGW toolchain,
hosted on Linux (Debian/Fedora).
The version of the Windows API that's currently targeted is Vista / Server
2008.
.. _HomeBrew: https://brew.sh/
.. _MacPorts: https://www.macports.org/
.. _Repology: https://repology.org/

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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
--------------------------------------
``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>``.
``-chardev`` backend aliases ``tty`` and ``parport`` (since 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
``tty`` and ``parport`` are aliases that will be removed. Instead, the
actual backend names ``serial`` and ``parallel`` should be used.
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``.
``--enable-fips`` (since 6.0)
'''''''''''''''''''''''''''''
This option restricts usage of certain cryptographic algorithms when
the host is operating in FIPS mode.
If FIPS compliance is required, QEMU should be built with the ``libgcrypt``
library enabled as a cryptography provider.
Neither the ``nettle`` library, or the built-in cryptography provider are
supported on FIPS enabled hosts.
``-writeconfig`` (since 6.0)
'''''''''''''''''''''''''''''
The ``-writeconfig`` option is not able to serialize the entire contents
of the QEMU command line. It is thus considered a failed experiment
and deprecated, with no current replacement.
Userspace local APIC with KVM (x86, since 6.0)
''''''''''''''''''''''''''''''''''''''''''''''
Using ``-M kernel-irqchip=off`` with x86 machine types that include a local
APIC is deprecated. The ``split`` setting is supported, as is using
``-M kernel-irqchip=off`` with the ISA PC machine type.
hexadecimal sizes with scaling multipliers (since 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
Input parameters that take a size value should only use a size suffix
(such as 'k' or 'M') when the base is written in decimal, and not when
the value is hexadecimal. That is, '0x20M' is deprecated, and should
be written either as '32M' or as '0x2000000'.
``-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.
``opened`` property of ``rng-*`` objects (since 6.0.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
The only effect of specifying ``opened=on`` in the command line or QMP
``object-add`` is that the device is opened immediately, possibly before all
other options have been processed. This will either have no effect (if
``opened`` was the last option) or cause errors. The property is therefore
useless and should not be specified.
``loaded`` property of ``secret`` and ``secret_keyring`` objects (since 6.0.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The only effect of specifying ``loaded=on`` in the command line or QMP
``object-add`` is that the secret is loaded immediately, possibly before all
other options have been processed. This will either have no effect (if
``loaded`` was the last option) or cause options to be effectively ignored as
if they were not given. The property is therefore useless and should not be
specified.
``-display sdl,window_close=...`` (since 6.1)
'''''''''''''''''''''''''''''''''''''''''''''
Use ``-display sdl,window-close=...`` instead (i.e. with a minus instead of
an underscore between "window" and "close").
``-no-quit`` (since 6.1)
''''''''''''''''''''''''
The ``-no-quit`` is a synonym for ``-display ...,window-close=off`` which
should be used instead.
QEMU Machine Protocol (QMP) commands
------------------------------------
``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.
``blockdev-add`` empty string argument ``backing`` (since 2.10.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use argument value ``null`` instead.
``block-commit`` arguments ``base`` and ``top`` (since 3.1.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
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``.
System accelerators
-------------------
MIPS ``Trap-and-Emul`` KVM support (since 6.0)
''''''''''''''''''''''''''''''''''''''''''''''
The MIPS ``Trap-and-Emul`` KVM host and guest support has been removed
from Linux upstream kernel, declare it deprecated.
System emulator CPUS
--------------------
``Icelake-Client`` CPU Model (since 5.2.0)
''''''''''''''''''''''''''''''''''''''''''
``Icelake-Client`` CPU Models are deprecated. Use ``Icelake-Server`` CPU
Models instead.
MIPS ``I7200`` CPU Model (since 5.2)
''''''''''''''''''''''''''''''''''''
The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
(the ISA has never been upstreamed to a compiler toolchain). Therefore
this CPU is also deprecated.
System emulator machines
------------------------
Raspberry Pi ``raspi2`` and ``raspi3`` machines (since 5.2)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The Raspberry Pi machines come in various models (A, A+, B, B+). To be able
to distinguish which model QEMU is implementing, the ``raspi2`` and ``raspi3``
machines have been renamed ``raspi2b`` and ``raspi3b``.
Aspeed ``swift-bmc`` machine (since 6.1)
''''''''''''''''''''''''''''''''''''''''
This machine is deprecated because we have enough AST2500 based OpenPOWER
machines. It can be easily replaced by the ``witherspoon-bmc`` or the
``romulus-bmc`` machines.
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 5.0.0)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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
--------------------
``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.
MIPS ``I7200`` CPU (since 5.2)
''''''''''''''''''''''''''''''
The ``I7200`` guest CPU relies on the nanoMIPS ISA, which is deprecated
(the ISA has never been upstreamed to a compiler toolchain). Therefore
this CPU is also deprecated.
Related binaries
----------------
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 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.
Guest Emulator ISAs
-------------------
nanoMIPS ISA
''''''''''''
The ``nanoMIPS`` ISA has never been upstreamed to any compiler toolchain.
As it is hard to generate binaries for it, declare it deprecated.

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About QEMU
==========
.. toctree::
:maxdepth: 2
build-platforms
deprecated
removed-features
license

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.. _License:
License
=======
QEMU is a trademark of Fabrice Bellard.
QEMU is released under the `GNU General Public
License <https://www.gnu.org/licenses/gpl-2.0.txt>`__, version 2. Parts
of QEMU have specific licenses, see file
`LICENSE <https://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE>`__.

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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.
``-no-kvm`` (removed in 5.2)
''''''''''''''''''''''''''''
The ``-no-kvm`` argument was a synonym for setting ``-machine accel=tcg``.
``-realtime`` (removed in 6.0)
''''''''''''''''''''''''''''''
The ``-realtime mlock=on|off`` argument has been replaced by the
``-overcommit mem-lock=on|off`` argument.
``-show-cursor`` option (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''
Use ``-display sdl,show-cursor=on``, ``-display gtk,show-cursor=on``
or ``-display default,show-cursor=on`` instead.
``-tb-size`` option (removed in 6.0)
''''''''''''''''''''''''''''''''''''
QEMU 5.0 introduced an alternative syntax to specify the size of the translation
block cache, ``-accel tcg,tb-size=``.
``-usbdevice audio`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''
This option lacked the possibility to specify an audio backend device.
Use ``-device usb-audio`` now instead (and specify a corresponding USB
host controller or ``-usb`` if necessary).
``-vnc acl`` (removed in 6.0)
'''''''''''''''''''''''''''''
The ``acl`` option to the ``-vnc`` argument has been replaced
by the ``tls-authz`` and ``sasl-authz`` options.
``-mon ...,control=readline,pretty=on|off`` (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``pretty=on|off`` switch has no effect for HMP monitors and
its use is rejected.
``-drive file=json:{...{'driver':'file'}}`` (removed 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''
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.
Floppy controllers' drive properties (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``-device floppy,...`` instead. When configuring onboard floppy
controllers
::
-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=...
When plugging in a floppy controller
::
-device isa-fdc,...,driveA=...
becomes
::
-device isa-fdc,...
-device floppy,unit=0,drive=...
and
::
-device isa-fdc,...,driveB=...
becomes
::
-device isa-fdc,...
-device floppy,unit=1,drive=...
``-drive`` with bogus interface type (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''
Drives with interface types other than ``if=none`` are for onboard
devices. Drives the board doesn't pick up can no longer be used with
-device. Use ``if=none`` instead.
``-usbdevice ccid`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''
This option was undocumented and not used in the field.
Use `-device usb-ccid`` instead.
RISC-V firmware not booted by default (removed in 5.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
QEMU 5.1 changes the default behaviour from ``-bios none`` to ``-bios default``
for the RISC-V ``virt`` machine and ``sifive_u`` machine.
QEMU Machine Protocol (QMP) commands
------------------------------------
``block-dirty-bitmap-add`` "autoload" parameter (removed in 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.
``change`` (removed in 6.0)
'''''''''''''''''''''''''''
Use ``blockdev-change-medium`` or ``change-vnc-password`` instead.
``query-events`` (removed in 6.0)
'''''''''''''''''''''''''''''''''
The ``query-events`` command has been superseded by the more powerful
and accurate ``query-qmp-schema`` command.
``migrate_set_cache_size`` and ``query-migrate-cache-size`` (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``migrate_set_parameter`` and ``info migrate_parameters`` instead.
``migrate_set_downtime`` and ``migrate_set_speed`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``migrate_set_parameter`` instead.
``query-cpus`` (removed in 6.0)
'''''''''''''''''''''''''''''''
The ``query-cpus`` command is replaced by the ``query-cpus-fast`` command.
``query-cpus-fast`` ``arch`` output member (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``arch`` output member of the ``query-cpus-fast`` command is
replaced by the ``target`` output member.
chardev client socket with ``wait`` option (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Character devices creating sockets in client mode should not specify
the 'wait' field, which is only applicable to sockets in server mode
``query-named-block-nodes`` result ``encryption_key_missing`` (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Removed with no replacement.
``query-block`` result ``inserted.encryption_key_missing`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Removed with no replacement.
``query-named-block-nodes`` and ``query-block`` result dirty-bitmaps[i].status (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``status`` field of the ``BlockDirtyInfo`` structure, returned by
these commands is removed. Two new boolean fields, ``recording`` and
``busy`` effectively replace it.
``query-block`` result field ``dirty-bitmaps`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by
the query-block command is itself now removed. 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.
``object-add`` option ``props`` (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''
Specify the properties for the object as top-level arguments instead.
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.
``change vnc TARGET`` (removed in 6.0)
''''''''''''''''''''''''''''''''''''''
No replacement. The ``change vnc password`` and ``change DEVICE MEDIUM``
commands are not affected.
``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, ``acl_remove`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``acl_show``, ``acl_reset``, ``acl_policy``, ``acl_add``, and
``acl_remove`` commands were removed with no replacement. Authorization
for VNC should be performed using the pluggable QAuthZ objects.
``migrate-set-cache-size`` and ``info migrate-cache-size`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``migrate-set-parameters`` and ``info migrate-parameters`` instead.
``migrate_set_downtime`` and ``migrate_set_speed`` (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
Use ``migrate-set-parameters`` instead.
``info cpustats`` (removed in 6.1)
''''''''''''''''''''''''''''''''''
This command didn't produce any output already. Removed with no replacement.
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.
``compat`` property of server class POWER CPUs (removed in 6.0)
'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``max-cpu-compat`` property of the ``pseries`` machine type should be used
instead.
``moxie`` CPU (removed in 6.1)
''''''''''''''''''''''''''''''
Nobody was using this CPU emulation in QEMU, and there were no test images
available to make sure that the code is still working, so it has been removed
without replacement.
``lm32`` CPUs (removed in 6.1.0)
''''''''''''''''''''''''''''''''
The only public user of this architecture was the milkymist project,
which has been dead for years; there was never an upstream Linux
port. Removed without replacement.
``unicore32`` CPUs (since 6.1.0)
''''''''''''''''''''''''''''''''
Support for this CPU was removed from the upstream Linux kernel, and
there is no available upstream toolchain to build binaries for it.
Removed without replacement.
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.
mips ``r4k`` platform (removed in 5.2)
''''''''''''''''''''''''''''''''''''''
This machine type was very old and unmaintained. Users should use the ``malta``
machine type instead.
mips ``fulong2e`` machine alias (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''
This machine has been renamed ``fuloong2e``.
``pc-1.0``, ``pc-1.1``, ``pc-1.2`` and ``pc-1.3`` (removed in 6.0)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
These machine types were very old and likely could not be used for live
migration from old QEMU versions anymore. Use a newer machine type instead.
linux-user mode CPUs
--------------------
``tilegx`` CPUs (removed in 6.0)
''''''''''''''''''''''''''''''''
The ``tilegx`` guest CPU support has been removed without replacement. It was
only implemented in linux-user mode, but support for this CPU was removed from
the upstream Linux kernel in 2018, and it has also been dropped from glibc, so
there is no new Linux development taking place with this architecture. For
running the old binaries, you can use older versions of QEMU.
System emulator devices
-----------------------
``ide-drive`` (removed in 6.0)
''''''''''''''''''''''''''''''
The 'ide-drive' device has been removed. Users should use 'ide-hd' or
'ide-cd' as appropriate to get an IDE hard disk or CD-ROM as needed.
``scsi-disk`` (removed in 6.0)
''''''''''''''''''''''''''''''
The 'scsi-disk' device has been removed. Users should use 'scsi-hd' or
'scsi-cd' as appropriate to get a SCSI hard disk or CD-ROM as needed.
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 explicitly 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*.
``-machine enforce-config-section=on|off`` (removed 5.2)
''''''''''''''''''''''''''''''''''''''''''''''''''''''''
The ``enforce-config-section`` property was replaced by the
``-global migration.send-configuration={on|off}`` option.
qemu-img amend to adjust backing file (removed in 6.1)
''''''''''''''''''''''''''''''''''''''''''''''''''''''
The use of ``qemu-img amend`` to modify the name or format of a qcow2
backing image 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). 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 (removed in 6.1)
'''''''''''''''''''''''''''''''''''''''''''''''''''''
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 requires 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 creating unsafe backing chains, 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.
Block devices
-------------
VXHS backend (removed in 5.1)
'''''''''''''''''''''''''''''
The VXHS code did not compile since v2.12.0. It was removed in 5.1.
``sheepdog`` driver (removed in 6.0)
''''''''''''''''''''''''''''''''''''
The corresponding upstream server project is no longer maintained.
Users are recommended to switch to an alternative distributed block
device driver such as RBD.