Re: Section X overlaps section Y problem.

[Jim Blandy <jimb at redhat dot com>]

Sergei Organov <osv@topconrd.ru> writes:
> Jim Blandy <jimb@redhat.com> writes:
> > Sergei Organov <osv@topconrd.ru> writes:
> > > On embedded target, to copy at startup some data and/or code from ROM to
> > > RAM at startup, I've been using the following technique that worked for
> > > me for years. The last version of binutils where I know it works is
> > > version 2.10.
> > 
> > So, your startup code copies the ROM contents (as given in .vect) into
> > RAM (covered by .vect_image).  Why do both of those sections have the
> > same LMA?
> 
> No, the opposite. Please take a look at the linker command file snippet
> once again (I've changed VECT memory region to be called RAM to avoid
> confusion): 
> 
>   [...]
>   .vect : AT(__vect_image) {
>     *(.vect)
>     . = ALIGN(16);
>   } > RAM
>   [...]
>   .vect_image : {
>     __vect_image = .;
>     . += SIZEOF(.vect);
>   } > ROM
>   [...]
> 
> .vect is in RAM but it's LMA is set to be equal to match the address of
> the fake section .vect_image that is entirely in ROM. The purpose of
> .vect_image is to provide the LMA value for .vect's AT() and to move
> current allocation address in the ROM forward by the size of the .vect
> section. At startup the SIZOF(.vect) bytes of data is copied from
> __vect_image address (=LMA of .vect) to the VMA of .vect.

Okay, I see now what you are doing.  Looking at the manual, I see that
one can also specify an LMA memory region, with AT>.  Perhaps you
could write your script like this:

   .vect : {
     *(.vect)
     . = ALIGN(16);
     __vect_image = LOADADDR(.vect);
   } > VECT AT> ROM

and omit .vect_image altogether.  But I haven't tried this.