Rationale of hardcoding resmgr_attr.msg_max_size in message_passing

[AEK2HI]

Description

In qnx_dispatch_engine, the msg_max_size is hardcoded to 2088 Bytes.

This leads to the problem that the max_send_size configuration of the client is not respected and the message_passing server discards messages bigger than 2088 bytes.

Can this can be made configurable?

Error Occurrence Rate

Reproducible

How to reproduce

The variable of concern is hard coded.
So the effect of discarded messages occurs every time this component is compiled and the binary is executed on QNX

Supporting Information

The variable is hardcoded in the following line of the dispatch engine:

communication/score/message_passing/qnx_dispatch/qnx_dispatch_engine.cpp

Line 141 in 29d6f94

resmgr_attr.msg_max_size = 2088U;

Classification

minor

Affected Version

v0.3.0

Category

• Safety Related
• Security Related

[castler]

@kitsnet can you Check?

[kitsnet]

While it's conceptually not easy to make this parameter configurable (as the relevant ServiceProtocolConfig is specified after this value is already used to allocate the relavant dispatch_context_t, it is possible to get around this limit by using resmgr_msgget() for messages that are longer than this limit. Just tried a proof of concept where it worked with message size 6000.

[AEK2HI]

@kitsnet Do you have your implementation using resmgr_msgget() on a branch that you would like to share?

[kitsnet]

@AEK2HI it was just a hack to prove feasibility of adding resmgr_msgget() to the existing QnxDispatchEngine::io_write() code to cover longer messages, not a clean implementation. By which time do you need this to be implemented?