Re: Link error with today's CVS binutils

[Eric DeVolder <devolder at evsx dot com>]

Geoff Keating wrote:

> > Date: Fri, 14 Jan 2000 10:39:34 -0600
> > From: Eric DeVolder <devolder@evsx.com>
>
> > I've built GCC 2.95.2 with today's CVS head for a ppc-elf as the target.
> > The software is a simple, fixed-address app that gets downloaded into
> > RAM of an eval board and then run. When linking, I get what I believe is
> > an error with the placement of the sections as directed by this linker
> > script:
> ...
> >     .klog (NOLOAD) :
> >     {
> >         PROVIDE (__KLOG_START = .);
> >         . = . + 0x00000400;
> >         PROVIDE (__KLOG_END = .);
> >     } > ram1
> >
> >     .data   :
> >     {
> >         PROVIDE (__DATA_RAM = .);
> >         PROVIDE (__DATA_ROM = .);
> >         PROVIDE (__DATA_START = .);
> >         *(.data)
> >         *(.got)                     /* to make the linker happy */
> >         PROVIDE (__DATA_END = .);
> >     } > ram1
> ...
> > The important thing to note here is that the .klog section is of length
> > 0x0400 and is placed into ram1, (0x00010000 to 0x000103FF). The .data
> > section is placed after .klog into ram1, and should start at 0x00010400.
>
> I'm not sure about that.  The .klog section isn't placed anywhere, you
> have specified NOLOAD.  Sections which are not loaded are allowed to
> overlap, for instance the stabs sections.  I may be wrong...
>
> --
> - Geoffrey Keating <geoffk@cygnus.com>

The GNU documentation says this:
The `(NOLOAD)' directive will mark a section to not be loaded at run time. The
linker will process the section normally, but will mark it so that a program
loader will not load it into memory.

I interpret this to mean that a NOLOAD section will still occupy space in the
memory map/image of the application, but won't get loaded (like .bss).

If my interpretation is correct (and the documentation is correct), then I
think NOLOAD isn't working correctly in the example I've provided.

Regardless, its behavior has changed from 2.9.1 to now. We need to correct
either the documentation or the linker.

Eric