From patchwork Wed Feb 26 11:30:33 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paolo Bonzini X-Patchwork-Id: 183913 Delivered-To: patch@linaro.org Received: by 2002:a92:1f12:0:0:0:0:0 with SMTP id i18csp3033001ile; Wed, 26 Feb 2020 03:41:56 -0800 (PST) X-Google-Smtp-Source: APXvYqxABAXwaoht0BZqeyDnI9+Jp6HyewuOTgjoSUYXLEkTkxkojE8RDdHfR4sFsQeHAHIOu1Kn X-Received: by 2002:a05:620a:8ca:: with SMTP id z10mr4237616qkz.242.1582717316486; Wed, 26 Feb 2020 03:41:56 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1582717316; cv=none; d=google.com; s=arc-20160816; b=Y0fhcEyqndReGwg+C8H8M6YJ6ldI5MvAbcHfA52Nbj0P7zM8iAlIRk2rVKT0uH4zvh LedDGjajKaPFbXiAuOroOZYARZJj/WyLHEehavI3jAfdorcYNRByDyY/hH8daD9Ffbmk 0zmm5lo+m7K3TSI/Tuwe+dgHHBYUW9uhTK2tCoX5NCqqlLFIJfJawzRy1xCxmTcDXvJJ +6e3pMqYgHOIEU833kzcpucp6EG5TUKoG8c2LYKewuGVZbvfGbVgNhYRK2jf4gmxHNL7 7LNFGIPUcb2NqjJcAUUTMhmXhecR7h26hAglFE943/QdcJHAOaEh7aXODcnZmMDtmGOO UQBQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=sender:errors-to:cc:list-subscribe:list-help:list-post:list-archive :list-unsubscribe:list-id:precedence:content-transfer-encoding :mime-version:references:in-reply-to:message-id:date:subject:to:from :dkim-signature; bh=DvH/hwbc52f9y/hSLLZgDpNon3UYB/InCyPExjWeA94=; b=RaLWpn/s9C9BwTAF9unhLxSxKPeu/O/uuIkWIMG8mBXcA1iAaCAQ6MEi+xYPUidIPT FUX0VIrhWv8Po8YebchfJKcuIuRvehnAlcAG4RaAz19k0E0u1hvOpd7NU3yh1cIQgj1V wvNsTtIFDytqr4d1164v5fa1Ix+Sez/lRp37FDMxMLDorgTzZ2+OyD6XL1gmkTgUwRE+ F8HVt9d+4rtGFQOnljDbqkjSKu5VPz0encq6nZp37+REm+qSgbbZH7gjfH5a47uHlxFu VzRpp/962FBY4PYG7VRjG8Jngp+reWRPRHWCy3vOv7cuZ5Q31/lP7eiGVXjbQs2qb1fg xorQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=fail header.i=@gmail.com header.s=20161025 header.b=LT8gRpUm; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+patch=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from lists.gnu.org (lists.gnu.org. [209.51.188.17]) by mx.google.com with ESMTPS id j18si956495qtk.120.2020.02.26.03.41.56 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Wed, 26 Feb 2020 03:41:56 -0800 (PST) Received-SPF: pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) client-ip=209.51.188.17; Authentication-Results: mx.google.com; dkim=fail header.i=@gmail.com header.s=20161025 header.b=LT8gRpUm; spf=pass (google.com: domain of qemu-devel-bounces+patch=linaro.org@nongnu.org designates 209.51.188.17 as permitted sender) smtp.mailfrom="qemu-devel-bounces+patch=linaro.org@nongnu.org"; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from localhost ([::1]:42876 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6v4d-0008W2-Vu for patch@linaro.org; Wed, 26 Feb 2020 06:41:56 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]:52914) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1j6uu2-0001A6-JN for qemu-devel@nongnu.org; Wed, 26 Feb 2020 06:31:01 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1j6utz-00078m-8y for qemu-devel@nongnu.org; Wed, 26 Feb 2020 06:30:58 -0500 Received: from mail-wm1-x343.google.com ([2a00:1450:4864:20::343]:39362) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1j6uty-00072i-Tm for qemu-devel@nongnu.org; Wed, 26 Feb 2020 06:30:55 -0500 Received: by mail-wm1-x343.google.com with SMTP id c84so2638034wme.4 for ; Wed, 26 Feb 2020 03:30:54 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=DvH/hwbc52f9y/hSLLZgDpNon3UYB/InCyPExjWeA94=; b=LT8gRpUmRg88IVJWhhL1Ekvg69XTlOQkxT5ktE51ZIX7YO8jqsWEldrruQVmUw59rk zOUGY72ZNl4Cm8sRGhFec+6jP+GIH9H+74PlH9jC/eMoCsZDC2MiRNgPd4YTCGQ08YRw C9iV0NDhNN85R9SwOJZuGpDu/C2pdEF4uc27peJ2UNtIzAQxcSnYUWm5t4hSyuMQ+wru B1u/hkbVZvd1jGwXVGoBBvJI6r0ybT0Wr+AhGCuf43+7DS6exyH0qA46hzbh2s8vEVsY ALMLjMlZdCWa+okBIfFJyvHHScHFfKjOgDFIGog4qPUzWReROuVDr9hpct8wGoj5iY5o 3ycw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=DvH/hwbc52f9y/hSLLZgDpNon3UYB/InCyPExjWeA94=; b=S+S6O2FeTy9Ah+p8VfdKJEXY7lxOWXoN3KZNT3pNJ6ZSXB0TAdQ5ry07l8LQXxY4Lc /KzELSS/gaVWM0dij78BFI+P3AGaOGDy2udPFEI6u6j2cEskHBSQwcYASgeTBxIo/RMC 0e9t4d1ByKucA9L8HEHrWlJW8jhSobxV20eOKmiwJkpuKe61XZoqWofw5zG2KUtg7OdZ anPvYA69lWPo9mAnVVNnSAbeME70fzkGUVML0mB5sjFKEfi/eaFOn6xUQ0KUBVmN2QDy jKLwsyPQYrQNu7kmBelkTkv+pvM+K7Y6y6Hln0oOGX2Swc+4DGxrZFFfXWvfnwu1CvHV tUuw== X-Gm-Message-State: APjAAAXWlzn9ywsSFB6ACXnWEVYMU8NE2M3RF8NDsthZHAl3NmMCA6oR wCngWlExp/g0HESEYfoh5RfKznPN X-Received: by 2002:a7b:c957:: with SMTP id i23mr5225493wml.174.1582716652529; Wed, 26 Feb 2020 03:30:52 -0800 (PST) Received: from donizetti.lan ([2001:b07:6468:f312:d0d9:ea10:9775:f33f]) by smtp.gmail.com with ESMTPSA id h128sm2628154wmh.33.2020.02.26.03.30.51 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 26 Feb 2020 03:30:51 -0800 (PST) From: Paolo Bonzini To: qemu-devel@nongnu.org Subject: [PATCH 17/18] docs/system: convert the documentation of deprecated features to rST. Date: Wed, 26 Feb 2020 12:30:33 +0100 Message-Id: <20200226113034.6741-18-pbonzini@redhat.com> X-Mailer: git-send-email 2.21.1 In-Reply-To: <20200226113034.6741-1-pbonzini@redhat.com> References: <20200226113034.6741-1-pbonzini@redhat.com> MIME-Version: 1.0 X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 2a00:1450:4864:20::343 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: peter.maydell@linaro.org Errors-To: qemu-devel-bounces+patch=linaro.org@nongnu.org Sender: "Qemu-devel" From: Peter Maydell 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 Signed-off-by: Paolo Bonzini --- docs/system/deprecated.rst | 446 +++++++++++++++++++++++++++++++++++++ docs/system/index.rst | 1 + 2 files changed, 447 insertions(+) create mode 100644 docs/system/deprecated.rst -- 2.21.1 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 `` - 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 b2263b70d8..467cda3e72 100644 --- a/docs/system/index.rst +++ b/docs/system/index.rst @@ -15,3 +15,4 @@ Contents: :maxdepth: 2 managed-startup security + deprecated