allow to preload data from a file into a memory region by specifying an input file in the XML

[wucke13]

I'd like to use memory regions to distribute data to my protection domains. Ideally, there would be a setting in the XML snippets of memory regions that specifies an input file. During execution of the microkit tool, the tool opens the input file, embeddeds its content into an ELF section and instructs the microkit loader to load from this section into the specific memory region during system initialization.

Why do this using Microkit instead of by a dedicated loader protection domain?

Because it allows to assume the correct data to be available in the mr from the first instruction executed in a protection domain! If a dedicated loader is used, than one can not just use the data in the mr, one can only start doing so after being signaled from the loader protection domain that the loading has succeeded. In my use case, I'd like to use the data from within the init() function, with the dedicated loader protection domain all my init logic that depends on the mr would have to be moved into the notified function. Also, the functionality is already there, to distribute the code of the individual protection domains.

Additional thoughts

• Should we also communicate the length of the file? If so, how?