Size of __po_hi_request_t is always the maximum

The size of the message buffers sent by the bus drivers is __PO_HI_MESSAGES_MAX_SIZE, which is calculated from sizeof(__po_hi_request_t). This type is a union of all the possible types in the function interfaces.

The consequence is that the size of the data sent via e.g. a serial line does not depend on which interfaces have been mapped through this serial line. Instead, it depends on the maximum data type size in the model.

For instance, if we have an interface in the model with a parameter of size 1kB which local inside a partition, and a second interface with a size of 1byte that is mapped to a serial line between two partitions, the serial line will send 1kB for each byte of actual data transferred.

This makes any data transfer between partitions unusable as soon as there are large types defined in the system, even if they are not actually transferred between partitions.