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* NEWS: Mention LMA default change. 

* ld.texinfo (Output Section LMA): Update default description.
	(Location Counter): Clarify backward movement.
	* ldlang.c (lang_size_sections_1): Leave non-alloc sections with
	default lma equal to vma.  Warn on backward movement of dot.
This commit is contained in:
Alan Modra 2006-08-22 07:41:05 +00:00
parent 0e2a4ebaf0
commit dc0b6aa05a
4 changed files with 53 additions and 11 deletions
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8
ld/ChangeLog
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@ -1,3 +1,11 @@
2006-08-22 Alan Modra <amodra@bigpond.net.au>
* NEWS: Mention LMA default change.
* ld.texinfo (Output Section LMA): Update default description.
(Location Counter): Clarify backward movement.
* ldlang.c (lang_size_sections_1): Leave non-alloc sections with
default lma equal to vma. Warn on backward movement of dot.
2006-08-22 Pedro Alves <pedro_alves@portugalmail.pt>
* Makefile.am: Split arm-wince into its own emulation.

6
ld/NEWS
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@ -1,4 +1,10 @@
-*- text -*-
* The default output section LMA has changed for allocatable sections from
being equal to VMA, to keeping the difference between LMA and VMA the same as
the previous output section in the same region. This is a more useful
default when using overlays and other cases where you specify an LMA
differing from the VMA for some sections.
* New switch: --print-gc-sections to list any sections removed by garabge
collection.

17
ld/ld.texinfo
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@ -3764,15 +3764,20 @@ Every section has a virtual address (VMA) and a load address (LMA); see
an output section description sets the VMA (@pxref{Output Section
Address}).
The linker will normally set the LMA equal to the VMA. You can change
that by using the @code{AT} keyword. The expression @var{lma} that
follows the @code{AT} keyword specifies the load address of the
section.
The expression @var{lma} that follows the @code{AT} keyword specifies
the load address of the section.
Alternatively, with @samp{AT>@var{lma_region}} expression, you may
specify a memory region for the section's load address. @xref{MEMORY}.
Note that if the section has not had a VMA assigned to it then the
linker will use the @var{lma_region} as the VMA region as well.
If neither @code{AT} nor @code{AT>} is specified for an allocatable
section, the linker will set the LMA such that the difference between
VMA and LMA for the section is the same as the preceding output
section in the same region. If there is no preceding output section
or the section is not allocatable, the linker will set the LMA equal
to the VMA.
@xref{Output Section Region}.
@cindex ROM initialized data
@ -4586,7 +4591,9 @@ anywhere that an ordinary symbol is allowed in an expression.
@cindex holes
Assigning a value to @code{.} will cause the location counter to be
moved. This may be used to create holes in the output section. The
location counter may never be moved backwards.
location counter may not be moved backwards inside an output section,
and may not be moved backwards outside of an output section if so
doing creates areas with overlapping LMAs.
@smallexample
SECTIONS

33
ld/ldlang.c
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@ -4400,16 +4400,30 @@ lang_size_sections_1
lma = align_power (lma, os->section_alignment);
os->bfd_section->lma = lma;
}
else if (r->last_os != NULL)
else if (r->last_os != NULL
&& (os->bfd_section->flags & SEC_ALLOC) != 0)
{
bfd_vma lma;
asection *last;
last = r->last_os->output_section_statement.bfd_section;
/* If dot moved backwards (which is invalid according
to ld docs) then leave lma equal to vma. This
keeps users of buggy ld scripts happy. */
if (dot >= last->vma)
/* A backwards move of dot should be accompanied by
an explicit assignment to the section LMA (ie.
os->load_base set) because backwards moves normally
create overlapping LMAs. */
if (dot < last->vma)
{
einfo (_("%P: warning: dot moved backwards before `%s'\n"),
os->name);
/* If dot moved backwards then leave lma equal to
vma. This is the old default lma, which might
just happen to work when the backwards move is
sufficiently large. Nag anyway, so people fix
their linker scripts. */
}
else
{
/* If the current vma overlaps the previous section,
then set the current lma to that at the end of
@ -4440,9 +4454,16 @@ lang_size_sections_1
lma region. We use this to set the lma for
following sections. Overlays or other linker
script assignment to lma might mean that the
default lma == vma is incorrect. */
default lma == vma is incorrect.
To avoid warnings about dot moving backwards when using
-Ttext, don't start tracking sections until we find one
of non-zero size or with lma set differently to vma. */
if (((os->bfd_section->flags & SEC_HAS_CONTENTS) != 0
|| (os->bfd_section->flags & SEC_THREAD_LOCAL) == 0)
&& (os->bfd_section->flags & SEC_ALLOC) != 0
&& (os->bfd_section->size != 0
|| os->bfd_section->vma != os->bfd_section->lma
|| r->last_os != NULL)
&& os->lma_region == NULL
&& !link_info.relocatable)
r->last_os = s;