ld and link scripts

[Moth Attack!]

I hope this is the correct place for a question about ld.  I'm using
a link script, and it seems that, within a section, data are always
aligned to the next 16 bytes.  I couldn't find anything about this
alignment in the documentation.  For example:

rom _rom_vma : AT(_rom_lma) {
   _rom_start = ABSOLUTE(.);
   *(rom);
   _rom_end = ABSOLUTE(.);
   _rom_length = _rom_end - _rom_start;
   }

If I use the above section, _rom_end is always rounded up to the
nearest 0x10, and therefore _rom_length is always a multiple of 16. 
This isn't a major problem, but I thought it was strange.  Can this
be changed?  Does it depend on the output architecture?

A bigger problem is that the extra bytes at the end are filled with
repeating copies of four random bytes.  FILL(0) and =0 both have no
effect on these bytes, but filling does work.  Another example:

rom _rom_vma : AT(_rom_lma) {
   *(rom);
   } = 0

This section will end with, e.g.:

12 34 56 78 00 00 a0 e1 00 00 a0 e1 00 00 a0 e1

The bytes "12 34 56 78" are the actual end of the section, and the
rest is filling to the next 0x10.  But if I do this:

rom _rom_vma : AT(_rom_lma) {
   *(rom);
   . = ALIGN(32);
   } = 0

This section will end with:

12 34 56 78 00 00 a0 e1 00 00 a0 e1 00 00 a0 e1
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00

So the =0 expression works.  It's just this 16-byte internal
alignment that's causing trouble.







                
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