A diversion: BSS regions

• ELF supports the C standard BSS regions, which are initialized to zero on load (for static variables, for example.)

• Instead of keeping a bunch of NULL in the ELF file, the Program Header can specify that the region data in the executable will be repeated to fill the region, so basically that's only one NULL which is used to set to zero an entire region.

• This makes the file smaller and faster to load.