Process loading

Processes loaded from a filesystem using the exec*(), posix_spawn() or spawn() calls are in ELF (Executable and Linking Format).

If the filesystem is on a block-oriented device, the code and data are loaded into main memory. By default, the memory pages containing the binaries are demand-loaded, but you can use the procnto -m option to change this; for more information, see Locking memory,” later in this chapter.

If the filesystem is memory mapped (e.g., ROM/flash image), the code needn't be loaded into RAM, but may be executed in place. This approach makes all RAM available for data and stack, leaving the code in ROM or flash. In all cases, if the same process is loaded more than once, its code will be shared.