xemu/docs
Markus Armbruster a3c45b3e62 qapi: New special feature flag "unstable"
By convention, names starting with "x-" are experimental.  The parts
of external interfaces so named may be withdrawn or changed
incompatibly in future releases.

The naming convention makes unstable interfaces easy to recognize.
Promoting something from experimental to stable involves a name
change.  Client code needs to be updated.  Occasionally bothersome.

Worse, the convention is not universally observed:

* QOM type "input-barrier" has properties "x-origin", "y-origin".
  Looks accidental, but it's ABI since 4.2.

* QOM types "memory-backend-file", "memory-backend-memfd",
  "memory-backend-ram", and "memory-backend-epc" have a property
  "x-use-canonical-path-for-ramblock-id" that is documented to be
  stable despite its name.

We could document these exceptions, but documentation helps only
humans.  We want to recognize "unstable" in code, like "deprecated".

So support recognizing it the same way: introduce new special feature
flag "unstable".  It will be treated specially by the QAPI generator,
like the existing feature flag "deprecated", and unlike regular
feature flags.

This commit updates documentation and prepares tests.  The next commit
updates the QAPI schema.  The remaining patches update the QAPI
generator and wire up -compat policy checking.

Management applications can then use query-qmp-schema and -compat to
manage or guard against use of unstable interfaces the same way as for
deprecated interfaces.

docs/devel/qapi-code-gen.txt no longer mandates the naming convention.
Using it anyway might help writers of programs that aren't
full-fledged management applications.  Not using it can save us
bothersome renames.  We'll see how that shakes out.

Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-Id: <20211028102520.747396-2-armbru@redhat.com>
2021-10-29 15:55:52 +02:00
..
_templates docs: Add QEMU version information to HTML footer 2021-07-18 10:59:47 +01:00
about qapi: Enable enum member introspection to show more than name 2021-10-27 17:18:43 +02:00
config docs: Grammar and spelling fixes 2018-07-13 10:16:04 +01:00
devel qapi: New special feature flag "unstable" 2021-10-29 15:55:52 +02:00
interop docs: standardize directory index to --- with overline 2021-09-13 13:56:26 +02:00
specs docs: standardize directory index to --- with overline 2021-09-13 13:56:26 +02:00
sphinx qapidoc: introduce QAPISchemaIfCond.docgen() 2021-08-26 13:53:56 +02:00
sphinx-static sphinx: adopt kernel readthedoc theme 2021-05-14 15:05:03 +04:00
spin docs: create config/, devel/ and spin/ subdirectories 2017-06-07 18:22:03 +02:00
system docs: Add documentation for vhost based RNG implementation 2021-10-20 04:37:55 -04:00
tools virtiofsd: xattr mapping add a new type "unsupported" 2021-10-25 18:48:23 +01:00
user docs: standardize directory index to --- with overline 2021-09-13 13:56:26 +02:00
amd-memory-encryption.txt docs: Add SEV-ES documentation to amd-memory-encryption.txt 2021-06-17 14:11:06 -04:00
block-replication.txt colo: Update Documentation for continuous replication 2020-03-03 18:04:47 +08:00
bypass-iommu.txt docs: Add documentation for iommu bypass 2021-07-16 11:10:45 -04:00
can.txt docs: Fix some typos (found by codespell) 2020-11-18 09:29:41 +01:00
ccid.txt hw/usb/ccid: remove references to NSS 2021-07-14 14:33:53 +01:00
COLO-FT.txt docs: update to show preferred boolean syntax for -cpu 2021-02-25 14:14:33 +01:00
colo-proxy.txt docs: update to show preferred boolean syntax for -chardev 2021-02-25 14:14:33 +01:00
conf.py docs: Fix documentation Copyright date 2021-07-18 10:59:46 +01:00
confidential-guest-support.txt s390: Recognize confidential-guest-support option 2021-02-08 16:57:38 +11:00
defs.rst.inc docs: Fix typo in the default name of the qemu-system-x86_64 binary 2021-04-01 14:28:39 +02:00
hyperv.txt i386: Change the default Hyper-V version to match WS2016 2021-10-01 19:04:45 +02:00
igd-assign.txt vfio/pci: Add IGD documentation 2016-05-26 11:12:05 -06:00
image-fuzzer.txt docs: List all image elements currently supported by the fuzzer 2014-09-22 11:39:35 +01:00
index.rst docs: standardize book titles to === with overline 2021-09-13 13:56:26 +02:00
memory-hotplug.txt docs: Grammar and spelling fixes 2018-07-13 10:16:04 +01:00
meson.build trace: move configuration from configure to Meson 2021-10-14 09:50:56 +02:00
multi-thread-compression.txt Replace '-enable-kvm' with '-accel kvm' in docs and help texts 2018-06-28 19:05:32 +02:00
multiseat.txt tests/docker/test-mingw and docs: Remove --with-sdlabi=2.0 2019-02-04 15:25:21 +00:00
nvdimm.txt docs/nvdimm: Update nvdimm option value in machine example 2021-09-27 10:57:21 +02:00
papr-pef.txt spapr: Add PEF based confidential guest support 2021-02-08 16:57:38 +11:00
pci_expander_bridge.txt pxb: cleanup 2016-03-11 16:59:12 +02:00
pcie_pci_bridge.txt docs: add slot when adding new PCIe root port 2021-07-03 03:12:35 -04:00
pcie.txt docs: pcie: Spell out machine type needs for PCIe features 2018-03-01 16:25:37 +02:00
pvrdma.txt docs: Fix broken links 2020-09-01 09:31:33 +02:00
qcow2-cache.txt qcow2: Document the Extended L2 Entries feature 2020-08-25 08:33:20 +02:00
qdev-device-use.txt hw/ide: remove 'ide-drive' device 2021-03-18 09:22:55 +00:00
qemu_logo.pdf docs: add qemu logo to pdf 2017-01-16 10:11:43 +01:00
qemu-option-trace.rst.inc qemu-option-trace.rst.inc: Don't use option:: markup 2020-11-02 16:52:18 +00:00
qemupciserial.inf docs: Grammar and spelling fixes 2018-07-13 10:16:04 +01:00
rdma.txt migrate: remove QMP/HMP commands for speed, downtime and cache size 2021-03-18 09:22:55 +00:00
replay.txt docs: Fix some typos (found by codespell) 2020-11-18 09:29:41 +01:00
spice-port-fqdn.txt docs: add spice-port-fqdn.txt 2012-12-17 14:01:41 +01:00
throttle.txt docs: Document the throttle block filter 2020-10-02 15:46:40 +02:00
u2f.txt hw/usb: Add U2F device autoscan to passthru mode 2020-08-31 08:23:39 +02:00
virtio-balloon-stats.txt Remove the deprecated -balloon option 2018-08-31 09:52:13 +02:00
xbzrle.txt migrate: remove QMP/HMP commands for speed, downtime and cache size 2021-03-18 09:22:55 +00:00
xen-save-devices-state.txt Fix up dangling references to qmp-commands.* in comment and doc 2018-03-02 13:48:26 -06:00