In a dynamic linking system you can build dynamic modules that are loaded and relocated by a dynamic loader at run time. The dynamic loader can also perform dynamic symbol resolution: resolving symbol references from dynamic modules with the symbol definitions from other dynamic modules. The dynamic linking model supports the creation of such dynamic modules. In particular, it supports creating dynamic executables and dynamic libraries.
A dynamic executable:
A dynamic library:
If we convert the earlier RTOS example into a dynamic system, the RTOS part of the system is still built like an executable and is assumed to be loaded by traditional means (bootstrap loader) and set running on the DSP by a host application.
Application tasks can be built as dynamic libraries that can then be loaded by the dynamic loader and linked against the RTOS that is already loaded and running on the DSP. In this scenario, the RTOS is a dynamic executable and is also sometimes referred to as the base image. The dynamic library is dynamically linked against the RTOS base image at load time.
In Figure 8-8, the dynamic loader is running on a General Purpose Processor (GPP) and is able to interact with the user to load and unload dynamic library components onto the DSP as needed. Another scenario is to load the dynamic loader as part of the RTOS base image executable:
An example of this scenario is the reference implementation of the C6000 dynamic loader. It is written to be built and run as a dynamic executable base image itself. It contains an interactive user interface which allows the user to identify their own base image, load and link dynamic libraries against that base image, and then execute a function that is defined in the dynamic library. For more details about the reference implementation of the dynamic loader, please see the Dynamic Loader wiki article at https://processors.wiki.ti.com/index.php/C6000_Dynamic_Loader.