docs/system: convert the documentation of deprecated features to rST.

We put the whole of this document into the system manual, though
technically a few parts of it apply to qemu-img or qemu-nbd which are
otherwise documented in tools/.

We only make formatting fixes, except for one use of 'appendix' which
we change to 'section' because this isn't an appendix in the Sphinx
manual.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Tested-by: Alex Bennée <alex.bennee@linaro.org>
Message-id: 20200228153619.9906-19-peter.maydell@linaro.org
Message-id: 20200226113034.6741-18-pbonzini@redhat.com

2 files changed, 447 insertions, 0 deletions

diff --git a/docs/system/deprecated.rst b/docs/system/deprecated.rst
new file mode 100644
index 0000000000..1eaa559079
--- /dev/null
+++ b/docs/system/deprecated.rst
@@ -0,0 +1,446 @@
+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 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.
+
+System emulator command line arguments
+--------------------------------------
+
+``-machine enforce-config-section=on|off`` (since 3.1)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``enforce-config-section`` parameter is replaced by the
+``-global migration.send-configuration={on|off}`` option.
+
+``-no-kvm`` (since 1.3.0)
+'''''''''''''''''''''''''
+
+The ``-no-kvm`` argument is now a synonym for setting ``-accel tcg``.
+
+``-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.
+
+``-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.
+
+``-net ...,name=``\ *name* (since 3.1)
+''''''''''''''''''''''''''''''''''''''
+
+The ``name`` parameter of the ``-net`` option is a synonym
+for the ``id`` parameter, which should now be used instead.
+
+``-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 *n* <= *sockets* * *cores* * *threads* < *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.
+*sockets* * *cores* * *threads* = *maxcpus*.
+
+``-vnc acl`` (since 4.0.0)
+''''''''''''''''''''''''''
+
+The ``acl`` option to the ``-vnc`` argument has been replaced
+by the ``tls-authz`` and ``sasl-authz`` options.
+
+``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=`` propery if you plan to
+transmit audio through the VNC protocol.
+
+``-mon ...,control=readline,pretty=on|off`` (since 4.1)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``pretty=on|off`` switch has no effect for HMP monitors, but is
+silently ignored. Using the switch with HMP monitors will become an
+error in the future.
+
+``-realtime`` (since 4.1)
+'''''''''''''''''''''''''
+
+The ``-realtime mlock=on|off`` argument has been replaced by the
+``-overcommit mem-lock=on|off`` argument.
+
+``-numa node,mem=``\ *size* (since 4.1)
+'''''''''''''''''''''''''''''''''''''''
+
+The parameter ``mem`` of ``-numa node`` is used to assign a part of
+guest RAM to a NUMA node. But when using it, it's impossible to manage specified
+RAM chunk on the host side (like bind it to a host node, setting bind policy, ...),
+so guest end-ups with the fake NUMA configuration with suboptiomal performance.
+However since 2014 there is an alternative way to assign RAM to a NUMA node
+using parameter ``memdev``, which does the same as ``mem`` and adds
+means to actualy manage node RAM on the host side. Use parameter ``memdev``
+with *memory-backend-ram* backend as an 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.
+In future new machine versions will not accept the option but it will still
+work with old machine types. User can check QAPI schema to see if the legacy
+option is supported by looking at MachineInfo::numa-mem-supported property.
+
+``-numa`` node (without memory specified) (since 4.1)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Splitting RAM by default between NUMA nodes has the same issues as ``mem``
+parameter described above 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 explictly instead.
+
+``-mem-path`` fallback to RAM (since 4.1)
+'''''''''''''''''''''''''''''''''''''''''
+
+Currently if guest RAM allocation from file pointed by ``mem-path``
+fails, QEMU falls back to allocating from RAM, which might result
+in unpredictable behavior since the backing file specified by the user
+is ignored. In the future, users will be responsible for making sure
+the backing storage specified with ``-mem-path`` can actually provide
+the guest RAM configured with ``-m`` and QEMU will fail to start up if
+RAM allocation is unsuccessful.
+
+RISC-V ``-bios`` (since 4.1)
+''''''''''''''''''''''''''''
+
+QEMU 4.1 introduced support for the -bios option in QEMU for RISC-V for the
+RISC-V virt machine and sifive_u machine.
+
+QEMU 4.1 has no changes to the default behaviour to avoid breakages. This
+default will change in a future QEMU release, so please prepare now. All users
+of the virt or sifive_u machine must change their command line usage.
+
+QEMU 4.1 has three options, please migrate to one of these three:
+ 1. ``-bios none`` - This is the current default behavior if no -bios option
+      is included. QEMU will not automatically load any firmware. It is up
+      to the user to load all the images they need.
+ 2. ``-bios default`` - In a future QEMU release this will become the default
+      behaviour if no -bios option is specified. This option will load the
+      default OpenSBI firmware automatically. The firmware is included with
+      the QEMU release and no user interaction is required. All a user needs
+      to do is specify the kernel they want to boot with the -kernel option
+ 3. ``-bios <file>`` - Tells QEMU to load the specified file as the firmwrae.
+
+``-tb-size`` option (since 5.0)
+'''''''''''''''''''''''''''''''
+
+QEMU 5.0 introduced an alternative syntax to specify the size of the translation
+block cache, ``-accel tcg,tb-size=``.  The new syntax deprecates the
+previously available ``-tb-size`` option.
+
+``-show-cursor`` option (since 5.0)
+'''''''''''''''''''''''''''''''''''
+
+Use ``-display sdl,show-cursor=on`` or
+ ``-display gtk,show-cursor=on`` instead.
+
+QEMU Machine Protocol (QMP) commands
+------------------------------------
+
+``change`` (since 2.5.0)
+''''''''''''''''''''''''
+
+Use ``blockdev-change-medium`` or ``change-vnc-password`` instead.
+
+``migrate_set_downtime`` and ``migrate_set_speed`` (since 2.8.0)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Use ``migrate-set-parameters`` instead.
+
+``migrate-set-cache-size`` and ``query-migrate-cache-size`` (since 2.11.0)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Use ``migrate-set-parameters`` and ``query-migrate-parameters`` instead.
+
+``query-block`` result field ``dirty-bitmaps[i].status`` (since 4.0)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``status`` field of the ``BlockDirtyInfo`` structure, returned by
+the query-block command is deprecated. Two new boolean fields,
+``recording`` and ``busy`` effectively replace it.
+
+``query-block`` result field ``dirty-bitmaps`` (Since 4.2)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``dirty-bitmaps`` field of the ``BlockInfo`` structure, returned by
+the query-block command is itself now deprecated. The ``dirty-bitmaps``
+field of the ``BlockDeviceInfo`` struct should be used instead, which is the
+type of the ``inserted`` field in query-block replies, as well as the
+type of array items in query-named-block-nodes.
+
+Since the ``dirty-bitmaps`` field is optionally present in both the old and
+new locations, clients must use introspection to learn where to anticipate
+the field if/when it does appear in command output.
+
+``query-cpus`` (since 2.12.0)
+'''''''''''''''''''''''''''''
+
+The ``query-cpus`` command is replaced by the ``query-cpus-fast`` command.
+
+``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.
+
+``cpu-add`` (since 4.0)
+'''''''''''''''''''''''
+
+Use ``device_add`` for hotplugging vCPUs instead of ``cpu-add``.  See
+documentation of ``query-hotpluggable-cpus`` for additional
+details.
+
+``query-events`` (since 4.0)
+''''''''''''''''''''''''''''
+
+The ``query-events`` command has been superseded by the more powerful
+and accurate ``query-qmp-schema`` command.
+
+chardev client socket with ``wait`` option (since 4.0)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+Character devices creating sockets in client mode should not specify
+the 'wait' field, which is only applicable to sockets in server mode
+
+Human Monitor Protocol (HMP) commands
+-------------------------------------
+
+The ``hub_id`` parameter of ``hostfwd_add`` / ``hostfwd_remove`` (since 3.1)
+''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The ``[hub_id name]`` parameter tuple of the 'hostfwd_add' and
+'hostfwd_remove' HMP commands has been replaced by ``netdev_id``.
+
+``cpu-add`` (since 4.0)
+'''''''''''''''''''''''
+
+Use ``device_add`` for hotplugging vCPUs instead of ``cpu-add``.  See
+documentation of ``query-hotpluggable-cpus`` for additional details.
+
+``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.
+
+Guest Emulator ISAs
+-------------------
+
+RISC-V ISA privledge specification version 1.09.1 (since 4.1)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The RISC-V ISA privledge specification version 1.09.1 has been deprecated.
+QEMU supports both the newer version 1.10.0 and the ratified version 1.11.0, these
+should be used instead of the 1.09.1 version.
+
+System emulator CPUS
+--------------------
+
+RISC-V ISA CPUs (since 4.1)
+'''''''''''''''''''''''''''
+
+The RISC-V cpus with the ISA version in the CPU name have been depcreated. The
+four CPUs are: ``rv32gcsu-v1.9.1``, ``rv32gcsu-v1.10.0``, ``rv64gcsu-v1.9.1`` and
+``rv64gcsu-v1.10.0``. Instead the version can be specified via the CPU ``priv_spec``
+option when using the ``rv32`` or ``rv64`` CPUs.
+
+RISC-V ISA CPUs (since 4.1)
+'''''''''''''''''''''''''''
+
+The RISC-V no MMU cpus have been depcreated. The two CPUs: ``rv32imacu-nommu`` and
+``rv64imacu-nommu`` should no longer be used. Instead the MMU status can be specified
+via the CPU ``mmu`` option when using the ``rv32`` or ``rv64`` CPUs.
+
+System emulator devices
+-----------------------
+
+``ide-drive`` (since 4.2)
+'''''''''''''''''''''''''
+
+The 'ide-drive' device is deprecated. Users should use 'ide-hd' or
+'ide-cd' as appropriate to get an IDE hard disk or CD-ROM as needed.
+
+``scsi-disk`` (since 4.2)
+'''''''''''''''''''''''''
+
+The 'scsi-disk' device is deprecated. Users should use 'scsi-hd' or
+'scsi-cd' as appropriate to get a SCSI hard disk or CD-ROM as needed.
+
+System emulator machines
+------------------------
+
+mips ``r4k`` platform (since 5.0)
+'''''''''''''''''''''''''''''''''
+
+This machine type is very old and unmaintained. Users should use the ``malta``
+machine type instead.
+
+``pc-1.0``, ``pc-1.1``, ``pc-1.2`` and ``pc-1.3`` (since 5.0)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+These machine types are very old and likely can not be used for live migration
+from old QEMU versions anymore. A newer machine type should be used instead.
+
+``spike_v1.9.1`` and ``spike_v1.10`` (since 4.1)
+''''''''''''''''''''''''''''''''''''''''''''''''
+
+The version specific Spike machines have been deprecated in favour of the
+generic ``spike`` machine. If you need to specify an older version of the RISC-V
+spec you can use the ``-cpu rv64gcsu,priv_spec=v1.9.1`` command line argument.
+
+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"}
+
+Related binaries
+----------------
+
+``qemu-img convert -n -o`` (since 4.2.0)
+''''''''''''''''''''''''''''''''''''''''
+
+All options specified in ``-o`` are image creation options, so
+they have no effect when used with ``-n`` to skip image creation.
+Silently ignored options can be confusing, so this combination of
+options will be made an error in future versions.
+
+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 te
+``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.
+
+
+Recently removed features
+=========================
+
+What follows is a record of recently removed, formerly deprecated
+features that serves as a record for users who have encountered
+trouble after a recent upgrade.
+
+QEMU Machine Protocol (QMP) commands
+------------------------------------
+
+``block-dirty-bitmap-add`` "autoload" parameter (since 4.2.0)
+'''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
+
+The "autoload" parameter has been ignored since 2.12.0. All bitmaps
+are automatically loaded from qcow2 images.
+
+Related binaries
+----------------
+
+``qemu-nbd --partition`` (removed in 5.0.0)
+'''''''''''''''''''''''''''''''''''''''''''
+
+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
diff --git a/docs/system/index.rst b/docs/system/index.rst
index d655344fff..f2f29fb6d2 100644
--- a/docs/system/index.rst
+++ b/docs/system/index.rst
@@ -16,3 +16,4 @@ Contents:
    managed-startup
    security
    vfio-ap
+   deprecated