GNU LD: Linker script generating incorrect address

[Erik Christiansen]

Hi Jens,

The relevant "info ld" section is "3.10.5 The Location Counter", which
makes the point that a '.' assignment inside an output section is
relative to the start of that section, _not_ absolute.

An expression like your "_lustack = _eustack - _sustack;" will provide
a size, because the difference is the same, whether the addresses are
absolute, or relative _and_ set in the current section.

One simple way to gain absolute addresses, is e.g.:

»    ABSOLUTE:  For an absolute symbol giving the address of the end of the
              output section .data:

                 .data : { *(.data) _edata = ABSOLUTE(.); }

              By default, _edata would be relative to the .data section.
«

Another way to make it absolute is the form appearing in many scripts:

   _edata = ADDR(.data) + SIZOF(.data) ;

The line should be placed outside (after) the .data section.

A third way which should work is:

   _edata = ADDR(.data) + _data_size ;

where _data_size is from an "__data_size = . ;" assignment within the
.data section. (i.e. assignments like yours, lacking the ABSOLUTE
operator. This last expression mixes absolute and relative values in a
workable way. (AIUI, (relative + absolute) = absolute, if the right
absolute is used, else it's an error, because you're missing a third
value.)

I haven't read your post in ultimate detail, so hope I have the nub of the
problem.

møjn,

Erik

-- 
Leibowitz's Rule:
When hammering a nail, you will never hit your finger if you hold the
hammer with both hands.