qemu-deprecated.texi - qemu - Git at Google

 @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
 ``-machine 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.

 @section QEMU Machine Protocol (QMP) commands

 @subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)

 "autoload" parameter is now ignored. All bitmaps are automatically loaded
 from qcow2 images.

 @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.

 @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 System emulator devices

 @subsection bluetooth (since 3.1)

 The bluetooth subsystem is unmaintained since many years and likely bitrotten
 quite a bit. It will be removed without replacement unless some users speaks
 up at the @email{qemu-devel@@nongnu.org} mailing list with information about
 their usecases.

 @section System emulator machines

 @subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)

 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.

 @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.
	@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
	``-machine 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.

	@section QEMU Machine Protocol (QMP) commands

	@subsection block-dirty-bitmap-add "autoload" parameter (since 2.12.0)

	"autoload" parameter is now ignored. All bitmaps are automatically loaded
	from qcow2 images.

	@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.

	@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 System emulator devices

	@subsection bluetooth (since 3.1)

	The bluetooth subsystem is unmaintained since many years and likely bitrotten
	quite a bit. It will be removed without replacement unless some users speaks
	up at the @email{qemu-devel@@nongnu.org} mailing list with information about
	their usecases.

	@section System emulator machines

	@subsection pc-0.12, pc-0.13, pc-0.14 and pc-0.15 (since 4.0)

	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.

	@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.