linker script or the one specified by using @samp{-T}). This feature
permits the linker to link against a file which appears to be an object
or an archive, but actually merely defines some symbol values, or uses
-@code{INPUT} or @code{GROUP} to load other objects. Note that
-specifying a script in this way merely augments the main linker script;
-use the @samp{-T} option to replace the default linker script entirely.
-@xref{Scripts}.
+@code{INPUT} or @code{GROUP} to load other objects. Specifying a
+script in this way merely augments the main linker script, with the
+extra commands placed after the main script; use the @samp{-T} option
+to replace the default linker script entirely, but note the effect of
+the @code{INSERT} command. @xref{Scripts}.
For options whose names are a single letter,
option arguments must either follow the option letter without intervening
@item --gc-sections
@itemx --no-gc-sections
Enable garbage collection of unused input sections. It is ignored on
-targets that do not support this option. This option is not compatible
-with @samp{-r} or @samp{--emit-relocs}. The default behaviour (of not
+targets that do not support this option. The default behaviour (of not
performing this garbage collection) can be restored by specifying
@samp{--no-gc-sections} on the command line.
+@samp{--gc-sections} decides which input sections are used by
+examining symbols and relocations. The section containing the entry
+symbol and all sections containing symbols undefined on the
+command-line will be kept, as will sections containing symbols
+referenced by dynamic objects. Note that when building shared
+libraries, the linker must assume that any visible symbol is
+referenced. Once this initial set of sections has been determined,
+the linker recursively marks as used any section referenced by their
+relocations. See @samp{--entry} and @samp{--undefined}.
+
+This option can be set when doing a partial link (enabled with option
+@samp{-r}). In this case the root of symbols kept must be explicitely
+specified either by an @samp{--entry} or @samp{--undefined} option or by
+a @code{ENTRY} command in the linker script.
+
@kindex --print-gc-sections
@kindex --no-print-gc-sections
@cindex garbage collection
by native linkers and cross linkers which have been configured with
the @option{--with-sysroot} option.
@item
-On an ELF system, if the @option{-rpath} and @code{rpath-link} options
-were not used, search the contents of the environment variable
-@code{LD_RUN_PATH}. It is for the native linker only.
+On an ELF system, for native linkers, if the @option{-rpath} and
+@option{-rpath-link} options were not used, search the contents of the
+environment variable @code{LD_RUN_PATH}.
@item
On SunOS, if the @option{-rpath} option was not used, search any
directories specified using @option{-L} options.
@item
-For a native linker, the contents of the environment variable
-@code{LD_LIBRARY_PATH}.
+For a native linker, the search the contents of the environment
+variable @code{LD_LIBRARY_PATH}.
@item
For a native ELF linker, the directories in @code{DT_RUNPATH} or
@code{DT_RPATH} of a shared library are searched for shared
to be made writable. This does not conform to the PE-COFF format
specification published by Microsoft.
+Note - use of the 'auto-import' extension will also cause read only
+data which would normally be placed into the .rdata section to be
+placed into the .data section instead. This is in order to work
+around a problem with consts that is described here:
+http://www.cygwin.com/ml/cygwin/2004-09/msg01101.html
+
Using 'auto-import' generally will 'just work' -- but sometimes you may
see this message:
command-line option: to make @code{ld} omit the assignment of addresses
to common symbols even for a non-relocatable output file.
+@item INSERT [ AFTER | BEFORE ] @var{output_section}
+@kindex INSERT
+@cindex insert user script into default script
+This command is typically used in a script specified by @samp{-T} to
+augment the default @code{SECTIONS} with, for example, overlays. It
+inserts all prior linker script statements after (or before)
+@var{output_section}, and also causes @samp{-T} to not override the
+default linker script. The exact insertion point is as for orphan
+sections. @xref{Location Counter}. The insertion happens after the
+linker has mapped input sections to output sections. Prior to the
+insertion, since @samp{-T} scripts are parsed before the default
+linker script, statements in the @samp{-T} script occur before the
+default linker script statements in the internal linker representation
+of the script. In particular, input section assignments will be made
+to @samp{-T} output sections before those in the default script. Here
+is an example of how a @samp{-T} script using @code{INSERT} might look:
+
+@smallexample
+SECTIONS
+@{
+ OVERLAY :
+ @{
+ .ov1 @{ ov1*(.text) @}
+ .ov2 @{ ov2*(.text) @}
+ @}
+@}
+INSERT AFTER .text;
+@end smallexample
+
@item NOCROSSREFS(@var{section} @var{section} @dots{})
@kindex NOCROSSREFS(@var{sections})
@cindex cross references
In the former case, the switch should not be used, and @samp{R_ARM_V4BX}
relocations are ignored.
+@cindex FIX_V4BX_INTERWORKING
+@kindex --fix-v4bx-interworking
+Replace @code{BX rM} instructions identified by @samp{R_ARM_V4BX}
+relocations with a branch to the following veneer:
+
+@smallexample
+TST rM, #1
+MOVEQ PC, rM
+BX Rn
+@end smallexample
+
+This allows generation of libraries/applications that work on ARMv4 cores
+and are still interworking safe. Note that the above veneer clobbers the
+condition flags, so may cause incorrect progrm behavior in rare cases.
+
@cindex USE_BLX
@kindex --use-blx
The @samp{--use-blx} switch enables the linker to use ARM/Thumb
projects / deliverable / binutils-gdb.git / blobdiff