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author | Peter Maydell <peter.maydell@linaro.org> | 2018-03-20 09:51:49 +0000 |
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committer | Peter Maydell <peter.maydell@linaro.org> | 2018-03-20 09:51:49 +0000 |
commit | 4bdc24fa018901892bb8a5bd1808ebd605f4c64d (patch) | |
tree | a8697528cea1222bf38abddf88b5746773adfcea /docs/devel/qapi-code-gen.txt | |
parent | c26ef39204f3200efe89470f6b21ac783edadd29 (diff) | |
parent | 02e3092db3f9b84ed6aae54e3b71d4dc4196c7eb (diff) | |
download | qemu-4bdc24fa018901892bb8a5bd1808ebd605f4c64d.tar.gz |
Merge remote-tracking branch 'remotes/ericb/tags/pull-qapi-2018-03-12-v4' into staging
qapi patches for 2018-03-12, 2.12 softfreeze
- Marc-André Lureau: 0/4 qapi: generate a literal qobject for introspection
- Max Reitz: 0/7 block: Handle null backing link
- Daniel P. Berrange: chardev: tcp: postpone TLS work until machine done
- Peter Xu: 00/23 QMP: out-of-band (OOB) execution support
- Vladimir Sementsov-Ogievskiy: 0/2 block latency histogram
- Eric Blake: qapi: Pass '-u' when doing non-silent diff
# gpg: Signature made Mon 19 Mar 2018 19:59:04 GMT
# gpg: using RSA key A7A16B4A2527436A
# gpg: Good signature from "Eric Blake <eblake@redhat.com>"
# gpg: aka "Eric Blake (Free Software Programmer) <ebb9@byu.net>"
# gpg: aka "[jpeg image of size 6874]"
# Primary key fingerprint: 71C2 CC22 B1C4 6029 27D2 F3AA A7A1 6B4A 2527 436A
* remotes/ericb/tags/pull-qapi-2018-03-12-v4: (38 commits)
qapi: Pass '-u' when doing non-silent diff
qapi: add block latency histogram interface
block/accounting: introduce latency histogram
tests: qmp-test: add oob test
tests: qmp-test: verify command batching
qmp: add command "x-oob-test"
monitor: enable IO thread for (qmp & !mux) typed
qmp: isolate responses into io thread
qmp: support out-of-band (oob) execution
qapi: introduce new cmd option "allow-oob"
monitor: send event when command queue full
qmp: add new event "command-dropped"
monitor: separate QMP parser and dispatcher
monitor: let suspend/resume work even with QMPs
monitor: let suspend_cnt be thread safe
monitor: introduce monitor_qmp_respond()
qmp: introduce QMPCapability
monitor: allow using IO thread for parsing
monitor: let mon_list be tail queue
monitor: unify global init
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Diffstat (limited to 'docs/devel/qapi-code-gen.txt')
-rw-r--r-- | docs/devel/qapi-code-gen.txt | 87 |
1 files changed, 72 insertions, 15 deletions
diff --git a/docs/devel/qapi-code-gen.txt b/docs/devel/qapi-code-gen.txt index 25b7180a18..a569d24745 100644 --- a/docs/devel/qapi-code-gen.txt +++ b/docs/devel/qapi-code-gen.txt @@ -554,9 +554,12 @@ following example objects: === Commands === +--- General Command Layout --- + Usage: { 'command': STRING, '*data': COMPLEX-TYPE-NAME-OR-DICT, '*returns': TYPE-NAME, '*boxed': true, - '*gen': false, '*success-response': false } + '*gen': false, '*success-response': false, + '*allow-oob': true } Commands are defined by using a dictionary containing several members, where three members are most common. The 'command' member is a @@ -636,6 +639,49 @@ possible, the command expression should include the optional key 'success-response' with boolean value false. So far, only QGA makes use of this member. +A command can be declared to support Out-Of-Band (OOB) execution. By +default, commands do not support OOB. To declare a command that +supports it, the schema includes an extra 'allow-oob' field. For +example: + + { 'command': 'migrate_recover', + 'data': { 'uri': 'str' }, 'allow-oob': true } + +To execute a command with out-of-band priority, the client specifies +the "control" field in the request, with "run-oob" set to +true. Example: + + => { "execute": "command-support-oob", + "arguments": { ... }, + "control": { "run-oob": true } } + <= { "return": { } } + +Without it, even the commands that support out-of-band execution will +still be run in-band. + +Under normal QMP command execution, the following apply to each +command: + +- They are executed in order, +- They run only in main thread of QEMU, +- They have the BQL taken during execution. + +When a command is executed with OOB, the following changes occur: + +- They can be completed before a pending in-band command, +- They run in a dedicated monitor thread, +- They do not take the BQL during execution. + +OOB command handlers must satisfy the following conditions: + +- It executes extremely fast, +- It does not take any lock, or, it can take very small locks if all + critical regions also follow the rules for OOB command handler code, +- It does not invoke system calls that may block, +- It does not access guest RAM that may block when userfaultfd is + enabled for postcopy live migration. + +If in doubt, do not implement OOB execution support. === Events === @@ -739,10 +785,12 @@ references by name. QAPI schema definitions not reachable that way are omitted. The SchemaInfo for a command has meta-type "command", and variant -members "arg-type" and "ret-type". On the wire, the "arguments" -member of a client's "execute" command must conform to the object type -named by "arg-type". The "return" member that the server passes in a -success response conforms to the type named by "ret-type". +members "arg-type", "ret-type" and "allow-oob". On the wire, the +"arguments" member of a client's "execute" command must conform to the +object type named by "arg-type". The "return" member that the server +passes in a success response conforms to the type named by +"ret-type". When "allow-oob" is set, it means the command supports +out-of-band execution. If the command takes no arguments, "arg-type" names an object type without members. Likewise, if the command returns nothing, "ret-type" @@ -1319,18 +1367,27 @@ Example: #ifndef EXAMPLE_QMP_INTROSPECT_H #define EXAMPLE_QMP_INTROSPECT_H - extern const char example_qmp_schema_json[]; + extern const QLitObject qmp_schema_qlit; #endif $ cat qapi-generated/example-qapi-introspect.c [Uninteresting stuff omitted...] - const char example_qmp_schema_json[] = "[" - "{\"arg-type\": \"0\", \"meta-type\": \"event\", \"name\": \"MY_EVENT\"}, " - "{\"arg-type\": \"1\", \"meta-type\": \"command\", \"name\": \"my-command\", \"ret-type\": \"2\"}, " - "{\"members\": [], \"meta-type\": \"object\", \"name\": \"0\"}, " - "{\"members\": [{\"name\": \"arg1\", \"type\": \"[2]\"}], \"meta-type\": \"object\", \"name\": \"1\"}, " - "{\"members\": [{\"name\": \"integer\", \"type\": \"int\"}, {\"default\": null, \"name\": \"string\", \"type\": \"str\"}], \"meta-type\": \"object\", \"name\": \"2\"}, " - "{\"element-type\": \"2\", \"meta-type\": \"array\", \"name\": \"[2]\"}, " - "{\"json-type\": \"int\", \"meta-type\": \"builtin\", \"name\": \"int\"}, " - "{\"json-type\": \"string\", \"meta-type\": \"builtin\", \"name\": \"str\"}]"; + const QLitObject example_qmp_schema_qlit = QLIT_QLIST(((QLitObject[]) { + QLIT_QDICT(((QLitDictEntry[]) { + { "arg-type", QLIT_QSTR("0") }, + { "meta-type", QLIT_QSTR("event") }, + { "name", QLIT_QSTR("Event") }, + { } + })), + QLIT_QDICT(((QLitDictEntry[]) { + { "members", QLIT_QLIST(((QLitObject[]) { + { } + })) }, + { "meta-type", QLIT_QSTR("object") }, + { "name", QLIT_QSTR("0") }, + { } + })), + ... + { } + })); |