Re: [PATCH v2 07/20] mcd: Implement target initialization API

[Markus Armbruster <armbru@redhat.com>]

Mario Fleischmann <mario.fleischmann@lauterbach.com> writes:

> On 15.05.2025 15:02, Markus Armbruster wrote:
>
>> Mario Fleischmann <mario.fleischmann@lauterbach.com> writes:
>> 
>>> The target initialization API ensures that the requested and provided
>>> MCD versions are compatible.
>>>
>>> * implement mcd_initialize_f and mcd_qry_error_info_f in mcdserver
>>> * implement QMP stub functionality
>>> * add QTest
>>>
>>> Thanks to the QMP integration in QTest, function arguments and results
>>> can be (de)serialized automatically.
>>>
>>> Signed-off-by: Mario Fleischmann <mario.fleischmann@lauterbach.com>
>> 
>> [...]
>> 
>>> diff --git a/qapi/mcd.json b/qapi/mcd.json
>>> index 701fd03..7b42a74 100644
>>> --- a/qapi/mcd.json
>>> +++ b/qapi/mcd.json
>>> @@ -4,3 +4,186 @@
>>>  ##
>>>  # = Multi-Core Debug (MCD) API
>>>  ##
>>> +
>>> +
>>> +##
>>> +# == Definition of Structures
>>> +##
>>> +
>>> +
>>> +##
>>> +# @MCDAPIVersion:
>>> +#
>>> +# Structure type containing the MCD API version information of the tool.
>>> +#
>>> +# @v-api-major: API major version.
>>> +# @v-api-minor: API minor version.
>>> +# @author:      API name of the author of this MCD API version.
>>> +#
>>> +# Since: 9.1
>>> +##
>>> +{ 'struct': 'MCDAPIVersion',
>>> +  'data': {
>>> +    'v-api-major': 'uint16',
>>> +    'v-api-minor': 'uint16',
>>> +    'author':      'str' } }
>>> +
>>> +
>>> +##
>>> +# @MCDImplVersionInfo:
>>> +#
>>> +# Structure type containing the MCD API implementation information.
>>> +#
>>> +# @v-api:       Implemented API version.
>>> +# @v-imp-major: Major version number of this implementation.
>>> +# @v-imp-minor: Minor version number of this implementation.
>>> +# @v-imp-build: Build number of this implementation.
>>> +# @vendor:      Name of vendor of the implementation.
>>> +# @date:        String from __DATE__ macro at compile time.
>>> +#
>>> +# Since: 9.1
>>> +##
>>> +{ 'struct': 'MCDImplVersionInfo',
>>> +  'data': {
>>> +    'v-api'      : 'MCDAPIVersion',
>>> +    'v-imp-major': 'uint16',
>>> +    'v-imp-minor': 'uint16',
>>> +    'v-imp-build': 'uint16',
>>> +    'vendor'     : 'str',
>>> +    'date'       : 'str' } }
>>> +
>>> +
>>> +##
>>> +# @MCDErrorInfo:
>>> +#
>>> +# Structure type containing the error status and error event notification.
>>> +#
>>> +# @return-status: Return status from the last API call.
>>> +# @error-code:    Detailed error code from the last API call.
>>> +# @error-events:  Detailed event code from the last API call.
>>> +# @error-str:     Detailed error text string from the last API call.
>>> +#
>>> +# Since: 9.1
>>> +##
>>> +{ 'struct': 'MCDErrorInfo',
>>> +  'data': {
>>> +    'return-status': 'uint32',
>>> +    'error-code'   : 'uint32',
>>> +    'error-events' : 'uint32',
>>> +    'error-str'    : 'str' }}
>>> +
>>> +
>>> +##
>>> +# == Target Initialization API
>>> +##
>>> +
>>> +
>>> +##
>>> +# @MCDInitializeResult:
>>> +#
>>> +# Return value of @mcd-initialize.
>>> +#
>>> +# @return-status: Return code.
>>> +#
>>> +# @impl-info: Information about the QEMU build, its version and the version of
>>> +#             the implemented MCD API.
>>> +#
>>> +# Since: 9.1
>>> +##
>>> +{ 'struct': 'MCDInitializeResult',
>>> +  'data': {
>>> +    'return-status': 'uint32',
>>> +    '*impl-info'   : 'MCDImplVersionInfo' } }
>>> +
>>> +
>>> +##
>>> +# @mcd-initialize:
>>> +#
>>> +# Function initializing the interaction between a tool-side implementation and
>>> +# target-side implementation.
>>> +#
>>> +# @version-req: MCD API version as requested by an upper layer.
>>> +#
>>> +# Returns: @MCDInitializeResult
>>> +#
>>> +# Since: 9.1
>>> +#
>>> +# .. qmp-example::
>>> +#    :title: Check compatibility with MCD server
>>> +#
>>> +#     -> { "execute": "mcd-initialize",
>>> +#          "arguments": { "version-req": { "v-api-major": 1,
>>> +#                                          "v-api-minor": 1,
>>> +#                                          "author": "" } } }
>>> +#     <- {
>>> +#            "return": {
>>> +#                "impl-info": {
>>> +#                    "v-api": {
>>> +#                        "v-api-minor": 1,
>>> +#                        "v-api-major": 1,
>>> +#                        "author": "QEMU Release"
>>> +#                    },
>>> +#                    "vendor": "QEMU",
>>> +#                    "v-imp-minor": 2,
>>> +#                    "v-imp-major": 9,
>>> +#                    "v-imp-build": 0,
>>> +#                    "date": "Dec 18 2024"
>>> +#                },
>>> +#                "return-status": 0
>>> +#            }
>>> +#        }
>>> +##
>>> +{ 'command': 'mcd-initialize',
>>> +  'data': { 'version-req': 'MCDAPIVersion' },
>>> +  'returns': 'MCDInitializeResult' }
>>> +
>>> +
>>> +##
>>> +# @mcd-exit:
>>> +#
>>> +# Function cleaning up all core and server connections from a tool.
>>> +#
>>> +# Since: 9.1
>>> +##
>>> +{ 'command': 'mcd-exit' }
>>> +
>>> +
>>> +##
>>> +# == Core Connection API
>>> +##
>>> +
>>> +
>>> +##
>>> +# @mcd-qry-error-info:
>>> +#
>>> +# Function allowing the access to detailed error and/or event information after
>>> +# an API call.
>>> +#
>>> +# Returns: @MCDErrorInfo
>>> +#
>>> +# Since: 9.1
>>> +#
>>> +# .. qmp-example::
>>> +#    :title: Incompatible MCD versions
>>> +#
>>> +#     -> { "execute": "mcd-initialize",
>>> +#          "arguments": { "version-req": { "v-api-major": 2,
>>> +#                                          "v-api-minor": 0,
>>> +#                                          "author": "" } } }
>>> +#     <- {
>>> +#            "return": {
>>> +#                "return-status": 3
>>> +#            }
>>> +#        }
>>> +#     -> { "execute": "mcd-qry-error-info" }
>>> +#     <- {
>>> +#            "return": {
>>> +#                "error-str": "incompatible versions",
>>> +#                "error-code": 3840,
>>> +#                "error-events": 0,
>>> +#                "return-status": 3
>>> +#            }
>>> +#        }
>>> +##
>>> +{ 'command': 'mcd-qry-error-info',
>>> +  'returns': 'MCDErrorInfo' }
>> 
>> You define some types under "Definition of Structures", and some
>> elsewhere.  How do you decide what goes where?  Hmm, looks like you
>> mirror mcd/mcd_api.h.  Correct?
>
> Generally, mcd/qapi-schema.json is intended to stay as close as possible
> to mcd_api.h. However, there are a few exceptions.
>
> If a function "MCDFunction" from the MCD API has multiple return values,
> an additional QAPI struct with the naming scheme "MCDFunctionResult" is
> introduced which will be returned by "MCDFunction".
> Since this struct is intended to be used by only one function, it is
> defined directly before that function.
>
> If the type of an argument or return value cannot be serialized, most
> often because it is a pointer, it is changed to a type which is able to
> carry the same information. In most cases, an int carrying a unique
> identifier suffices. Sometimes, an additional struct is required.
> This struct can possibly be used by multiple functions, so I would
> expect it in the "Definition of Structures" section.

Makes sense.

Suggest to add a suitable varation of this explanation to the .json as a
non-doc comment.  Reminder:

##
# Doc comment
##

#
# Not a doc comment
#