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2023-05-22docs/interop: Convert qmp-spec.txt to rSTPeter Maydell
Convert the qmp-spec.txt document to restructuredText. Notable points about the conversion: * numbers at the start of section headings are removed, to match the style of the rest of the manual * cross-references to other sections or documents are hyperlinked * various formatting tweaks (notably the examples, which need the -> and <- prefixed so the QMP code-block lexer will accept them) * English prose fixed in a few places Reviewed-by: Eric Blake <eblake@redhat.com> Signed-off-by: Peter Maydell <peter.maydell@linaro.org> Message-Id: <20230515162245.3964307-2-peter.maydell@linaro.org> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> [.. code-block:: dumbed down to :: to work around CI failure]
2023-05-10docs/devel/qapi-code-gen: Update doc comment conventionsMarkus Armbruster
The commit before previous relaxed the indentation rules to let us improve the doc comment conventions. This commit changes the written conventions. The next commits will update QAPI schemas to conform to them. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230428105429.1687850-16-armbru@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
2023-05-10qapi: Relax doc string @name: description indentation rulesMarkus Armbruster
The QAPI schema doc comment language provides special syntax for command and event arguments, struct and union members, alternate branches, enumeration values, and features: descriptions starting with "@name:". By convention, we format them like this: # @name: Lorem ipsum dolor sit amet, consectetur adipiscing elit, # sed do eiusmod tempor incididunt ut labore et dolore # magna aliqua. Okay for names as short as "name", but we have much longer ones. Their description gets squeezed against the right margin, like this: # @dirty-sync-missed-zero-copy: Number of times dirty RAM synchronization could # not avoid copying dirty pages. This is between # 0 and @dirty-sync-count * @multifd-channels. # (since 7.1) The description text is effectively just 50 characters wide. Easy enough to read, but can be cumbersome to write. The awkward squeeze against the right margin makes people go beyond it, which produces two undesirables: arguments about style, and descriptions that are unnecessarily hard to read, like this one: # @postcopy-vcpu-blocktime: list of the postcopy blocktime per vCPU. This is # only present when the postcopy-blocktime migration capability # is enabled. (Since 3.0) We could instead format it like # @postcopy-vcpu-blocktime: # list of the postcopy blocktime per vCPU. This is only present # when the postcopy-blocktime migration capability is # enabled. (Since 3.0) or, since the commit before previous, like # @postcopy-vcpu-blocktime: # list of the postcopy blocktime per vCPU. This is only present # when the postcopy-blocktime migration capability is # enabled. (Since 3.0) However, I'd rather have # @postcopy-vcpu-blocktime: list of the postcopy blocktime per vCPU. # This is only present when the postcopy-blocktime migration # capability is enabled. (Since 3.0) because this is how rST field and option lists work. To get this, we need to let the first non-blank line after the "@name:" line determine expected indentation. This fills up the indentation pitfall mentioned in docs/devel/qapi-code-gen.rst. A related pitfall still exists. Update the text to show it. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230428105429.1687850-14-armbru@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> [Work around lack of walrus operator in Python 3.7 and older]
2023-05-09sphinx/qapidoc: Do not emit TODO sections into user manualsMarkus Armbruster
QAPI doc comments are for QMP users: they go into the "QEMU QMP Reference Manual" and the "QEMU Storage Daemon QMP Reference Manual". The doc comment TODO sections are for somebody else, namely for the people who can do: developers. Do not emit them into the user manuals. This elides the following TODOs: * SchemaInfoCommand # TODO: @success-response (currently irrelevant, because it's QGA, not QMP) This is a note to developers adding introspection to the guest agent. It makes no sense to users. * @query-hotpluggable-cpus # TODO: Better documentation; currently there is none. This is a reminder for developers. It doesn't help users. * @device_add # TODO: This command effectively bypasses QAPI completely due to its # "additional arguments" business. It shouldn't have been added to # the schema in this form. It should be qapified properly, or # replaced by a properly qapified command. Likewise. Eliding them is an improvement. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230428105429.1687850-7-armbru@redhat.com> Reviewed-by: Ani Sinha <anisinha@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
2023-05-09docs/devel/qapi-code-gen: Turn FIXME admonitions into commentsMarkus Armbruster
We have two FIXME notes. These FIXMEs are for QAPI developers. They are not useful for QAPI schema developers. They are marked up as admonitions, which makes them look important in generated HTML. Turn them into comments. QAPI developers will still see them (they read and write the .rst). QAPI schema developers may still see them (if they read the .rst instead of the generated .html), but "this is just for QAPI developers" should be more obvious. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230428105429.1687850-3-armbru@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
2023-05-09docs/devel/qapi-code-gen: Clean up use of quotes a bitMarkus Armbruster
Section "Definition documentation" uses both single and double quotes around doc text snippets. Stick to double quotes. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230428105429.1687850-2-armbru@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com>
2023-04-28docs/devel/qapi-code-gen: Describe some doc markup pitfallsMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230427095346.1238913-1-armbru@redhat.com> Reviewed-by: Juan Quintela <quintela@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
2023-04-28qapi: Fix bullet list markup in documentationMarkus Armbruster
Peter Maydell's commit 100cc4fe0f08 explains: rST insists on a blank line before and after a bulleted list [...] Add some extra blank lines in the doc comments so they're acceptable rST input. It missed one in qapi/trace.json. Paolo Bonzini later added another instance in qapi/stats.json, providing further, if unintended, evidence for his quip that rST is the Perl of ASCII-based markups. Both are parsed as ordinary paragraph, resulting in garbled output. John Snow missed the need for a blank line when converting docs/devel/qapi-code-gen.txt to rST. Add the blank lines we need to get the bullet lists recognized as such. Kevin Wolf and Lukas Straub added two more, but indented. Sphinx recognizes them as (indented) bullet lists. The indentation looks slightly off. Insert a blank line and delete the extra indentation. Fixes: 100cc4fe0f0827f8da1a5c05f9c65e2aaa40e03d (qapi: Add blank lines before bulleted lists) Fixes: 467ef823d83e (qmp: add filtering of statistics by target vCPU) Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20230425064223.820979-10-armbru@redhat.com> [Fix of docs/devel/qapi-code-gen.rst squashed, commit message adjusted]
2023-04-28qapi: @foo should be used to reference, not ``foo``Markus Armbruster
Documentation suggests @foo is merely shorthand for ``foo``. It's not, it carries additional meaning: it's a reference to a QAPI schema name. Reword the documentation to spell that out. Fix up the few ``foo`` that should be @foo. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20230425064223.820979-7-armbru@redhat.com>
2023-04-24qapi: Require boxed for conditional command and event argumentsMarkus Armbruster
The C code generator fails to honor 'if' conditions of command and event arguments. For instance, tests/qapi-schema/qapi-schema-test.json has { 'event': 'TEST_IF_EVENT', 'data': { 'foo': 'TestIfStruct', 'bar': { 'type': ['str'], 'if': 'TEST_IF_EVT_ARG' } }, 'if': { 'all': ['TEST_IF_EVT', 'TEST_IF_STRUCT'] } } Generated tests/test-qapi-events.h fails to honor the TEST_IF_EVT_ARG condition: #if defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT) void qapi_event_send_test_if_event(TestIfStruct *foo, strList *bar); #endif /* defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT) */ Only uses so far are in tests/. We could fix the generator to emit something like #if defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT) void qapi_event_send_test_if_event(TestIfStruct *foo #if defined(TEST_IF_EVT_ARG) , strList *bar #endif ); #endif /* defined(TEST_IF_EVT) && defined(TEST_IF_STRUCT) */ Ugly. Calls become similarly ugly. Not worth fixing. Conditional arguments work fine with 'boxed': true, simply because complex types with conditional members work fine. Not worth breaking. Reject conditional arguments unless boxed. Move the tests cases covering unboxed conditional arguments out of tests/qapi-schema/qapi-schema-test.json. Cover boxed conditional arguments there instead. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230316071325.492471-15-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com>
2023-02-23docs/devel/qapi-code-gen: Fix a missing 'may', clarify SchemaInfoMarkus Armbruster
Documentation of enumeration value conditions lacks a 'may'. Fix that. Clarify SchemaInfo documentation for struct and union types. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230213132009.918801-3-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com>
2023-02-23docs/devel/qapi-code-gen: Belatedly update features documentationMarkus Armbruster
Commit 013b4efc9be "qapi: Add feature flags to remaining definitions" (v5.0.0), commit 84ab0086879 "qapi: Add feature flags to struct members" (v5.0.0), and commit b6c18755e41 "qapi: Add feature flags to enum members" (v6.2.0) neglected to update section "Features". Make up for that. Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20230213132009.918801-2-armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com>
2022-12-13qapi: Start to elide redundant has_FOO in generated CMarkus Armbruster
In QAPI, absent optional members are distinct from any present value. We thus represent an optional schema member FOO as two C members: a FOO with the member's type, and a bool has_FOO. Likewise for function arguments. However, has_FOO is actually redundant for a pointer-valued FOO, which can be null only when has_FOO is false, i.e. has_FOO == !!FOO. Except for arrays, where we a null FOO can also be a present empty array. The redundant has_FOO are a nuisance to work with. Improve the generator to elide them. Uses of has_FOO need to be replaced as follows. Tests of has_FOO become the equivalent comparison of FOO with null. For brevity, this is commonly done by implicit conversion to bool. Assignments to has_FOO get dropped. Likewise for arguments to has_FOO parameters. Beware: code may violate the invariant has_FOO == !!FOO before the transformation, and get away with it. The above transformation can then break things. Two cases: * Absent: if code ignores FOO entirely when !has_FOO (except for freeing it if necessary), even non-null / uninitialized FOO works. Such code is known to exist. * Present: if code ignores FOO entirely when has_FOO, even null FOO works. Such code should not exist. In both cases, replacing tests of has_FOO by FOO reverts their sense. We have to fix the value of FOO then. To facilitate review of the necessary updates to handwritten code, add means to opt out of this change, and opt out for all QAPI schema modules where the change requires updates to handwritten code. The next few commits will remove these opt-outs in reviewable chunks, then drop the means to opt out. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20221104160712.3005652-5-armbru@redhat.com>
2022-12-13docs/devel/qapi-code-gen: Extend example for next commit's changeMarkus Armbruster
The next commit will change the code generated for some optional members. The example schema contains an optional member affected by the change. Add one that is not affected. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20221104160712.3005652-4-armbru@redhat.com>
2022-12-13qapi: Tidy up whitespace in generated codeMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20221104160712.3005652-3-armbru@redhat.com>
2022-12-13docs/devel/qapi-code-gen: Update example to match current codeMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Daniel P. Berrangé <berrange@redhat.com> Message-Id: <20221104160712.3005652-2-armbru@redhat.com>
2022-05-16docs/devel/qapi-code-gen: Belatedly document feature naming rulesMarkus Armbruster
Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20220510061645.3209195-3-armbru@redhat.com>
2022-04-21docs: qapi: Remove outdated reference to simple unionsAndrea Bolognani
Commit 4e99f4b12c0e dropped simple unions and updated most documentation accordingly, but in one case we still claim that there are "two flavors of unions". Signed-off-by: Andrea Bolognani <abologna@redhat.com> Message-Id: <20220420153408.243584-2-abologna@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2022-01-27docs/qapi-code-gen: update to cover trace events code generationVladimir Sementsov-Ogievskiy
Previous commits enabled trace events generation for most of QAPI generated code (except for tests/ and qga/). Let's update documentation to illustrate it. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Message-Id: <20220126161130.3240892-6-vsementsov@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2022-01-27qapi/commands: refactor error handling codeVladimir Sementsov-Ogievskiy
Move error_propagate() to if (err) and make "if (err)" block mandatory. This is to simplify further commit, which will bring trace events generation for QMP commands. Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20220126161130.3240892-3-vsementsov@virtuozzo.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2021-11-10docs/devel/qapi-code-gen: Belatedly document feature documentationMarkus Armbruster
Commit 6a8c0b5102 "qapi: Add feature flags to struct types" neglected to document how to document feature flags. Make up for that. Cc: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20211026111023.76937-3-armbru@redhat.com> [Editing accident fixed]
2021-11-10docs/devel/qapi-code-gen: Drop a duplicate paragraphMarkus Armbruster
Commit 55ec69f8b1 "docs/devel/qapi-code-gen.txt: Update to new rST backend conventions" accidentally duplicated a paragraph. Drop it. Cc: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20211026111023.76937-2-armbru@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com>
2021-10-29qapi: New special feature flag "unstable"Markus Armbruster
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>
2021-10-27qapi: Add feature flags to enum membersMarkus Armbruster
This is quite similar to commit 84ab008687 "qapi: Add feature flags to struct members", only for enums instead of structs. Special feature flag 'deprecated' is silently ignored there. This is okay only because it will be implemented shortly. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20211025042405.3762351-3-armbru@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com>
2021-10-27qapi: Enable enum member introspection to show more than nameMarkus Armbruster
The next commit will add feature flags to enum members. There's a problem, though: query-qmp-schema shows an enum type's members as an array of member names (SchemaInfoEnum member @values). If it showed an array of objects with a name member, we could simply add more members to these objects. Since it's just strings, we can't. I can see three ways to correct this design mistake: 1. Do it the way we should have done it, plus compatibility goo. We want a ['SchemaInfoEnumMember'] member in SchemaInfoEnum. Since changing @values would be a compatibility break, add a new member @members instead. @values is now redundant. In my testing, output of qemu-system-x86_64's query-qmp-schema grows by 11% (18.5KiB). We can deprecate @values now and drop it later. This will break outmoded clients. Well-behaved clients such as libvirt are expected to break cleanly. 2. Like 1, but omit "boring" elements of @member, and empty @member. @values does not become redundant. @members augments it. Somewhat cumbersome, but output of query-qmp-schema grows only as we make enum members non-boring. There is nothing to deprecate here. 3. Versioned query-qmp-schema. query-qmp-schema provides either @values or @members. The QMP client can select which version it wants. There is no redundant output. We can deprecate old versions and eventually drop them. This will break outmoded clients. Breaking cleanly is easier than for 1. While 1 and 2 operate within the common rules for compatible evolution apply (section "Compatibility considerations" in docs/devel/qapi-code-gen.rst), 3 bypasses them. Attractive when operating within the rules is just too awkward. Not the case here. This commit implements 1. Libvirt developers prefer it. Deprecate @values in favour of @members. Since query-qmp-schema compatibility is pretty fundamental for management applications, an extended grace period is advised. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Tested-by: Peter Krempa <pkrempa@redhat.com> Acked-by: Peter Krempa <pkrempa@redhat.com> Message-Id: <20211025042405.3762351-2-armbru@redhat.com> Reviewed-by: John Snow <jsnow@redhat.com>
2021-09-27qapi: Drop simple unionsMarkus Armbruster
Simple unions predate flat unions. Having both complicates the QAPI schema language and the QAPI generator. We haven't been using simple unions in new code for a long time, because they are less flexible and somewhat awkward on the wire. The previous commits eliminated simple union from the tree. Now drop them from the QAPI schema language entirely, and update mentions of "flat union" to just "union". Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Message-Id: <20210917143134.412106-22-armbru@redhat.com>
2021-09-25qapi: Tidy up unusual line breaksMarkus Armbruster
Break lines between members instead of within members. Signed-off-by: Markus Armbruster <armbru@redhat.com> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com> Message-Id: <20210917143134.412106-2-armbru@redhat.com>
2021-08-26docs: update the documentation upfront about schema configurationMarc-André Lureau
Update the documentation describing the changes in this series. Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Tested-by: John Snow <jsnow@redhat.com> Reviewed-by: Markus Armbruster <armbru@redhat.com> Message-Id: <20210804083105.97531-2-marcandre.lureau@redhat.com> [Rebased with straightforward conflicts] Signed-off-by: Markus Armbruster <armbru@redhat.com>
2021-08-04docs/qapi-code-gen: add cross-referencesJohn Snow
Add clickables to many places. Signed-off-by: John Snow <jsnow@redhat.com> Message-Id: <20210720235619.2048797-4-jsnow@redhat.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2021-08-04docs/qapi-code-gen: Beautify formattingJohn Snow
Mostly, add ``literal`` markers to a lot of things like C types, add code blocks, and fix the way a few things render. Signed-off-by: John Snow <jsnow@redhat.com> Message-Id: <20210720235619.2048797-3-jsnow@redhat.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Markus Armbruster <armbru@redhat.com>
2021-08-04docs: convert qapi-code-gen.txt to ReSTJohn Snow
This is a very rudimentary conversion from .txt to .rst changing as little as possible, but getting it to render somewhat nicely; without using any Sphinx directives. (It is 'native' ReST.) Further patches will add cross-references and Sphinx-specific extensions to make it sparkle. Signed-off-by: John Snow <jsnow@redhat.com> Message-Id: <20210720235619.2048797-2-jsnow@redhat.com> Reviewed-by: Peter Maydell <peter.maydell@linaro.org> Signed-off-by: Markus Armbruster <armbru@redhat.com>