docs/system/deprecated.rst - third_party/qemu - Git at Google

 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.

 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.

 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.


 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
 --------------------

 ``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.

 ``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.

 ``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``.

 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"}

 ``sheepdog`` driver (since 5.2.0)
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

 The ``sheepdog`` block device driver is deprecated. The corresponding upstream
 server project is no longer actively maintained. Users are recommended to switch
 to an alternative distributed block device driver such as RBD. The
 ``qemu-img convert`` command can be used to liberate existing data by moving
 it out of sheepdog volumes into an alternative storage backend.

 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
 ----------------

 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 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.
	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.

	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.

	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.


	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
	--------------------

	``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.

	``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.

	``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``.

	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"}

	``sheepdog`` driver (since 5.2.0)
	^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

	The ``sheepdog`` block device driver is deprecated. The corresponding upstream
	server project is no longer actively maintained. Users are recommended to switch
	to an alternative distributed block device driver such as RBD. The
	``qemu-img convert`` command can be used to liberate existing data by moving
	it out of sheepdog volumes into an alternative storage backend.

	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
	----------------

	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 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.