i think this is due to things like this appearing in the ELF ld scripts:
     . = 0x08048000 + SIZEOF_HEADERS;
   
   
   i would like to know where this magic 0x08048000 number comes from
   and what the ~128MB of address space before "start" is supposed to be 
   used for now.  does anyone know?


as jason hinted, this is from ELF basically.  as i understand it,
it was chosen so that the stack could grown downwards from the
bottom of the program, thus allowing a single region for mapping.
but it occurs to me that this is incongruent with r/o text
mappings vs. r/w data/stack mappings...


levine's "linkers & loaders" book explains it but i don't have my
copy handy...