download_helper File

download_helper enables programs to be downloaded to the memory used by a domain instead of BBSRAM. This provides an environment in which host programs can run without having to know how to relocate themselves to memory. These programs can be larger than BBSRAM.

download_helper works by running a protocol through a mailbox in BBSRAM. The protocol has commands for allocating and mapping physical to virtual memory, and for moving data between a buffer in BBSRAM and virtual memory. When complete, the thread of execution is usually passed to the new program at an entry point provided by the SSP. After this occurs, download_helper lives on in BBSRAM so it can provide reset handling services. Normally, you do not need to be concerned with the download helper; it is used only by the obp_helper(1M) daemon. See the obp_helper(1M) man page for more information.