@ifset HPPA
* HPPA ELF32:: ld and HPPA 32-bit ELF
@end ifset
+@ifset M68HC11
+* M68HC11/68HC12:: ld and the Motorola 68HC11 and 68HC12 families
+@end ifset
@ifset TICOFF
* TI COFF:: ld and the TI COFF
@end ifset
@samp{0} for base 8). @xref{Entry Point}, for a discussion of defaults
and other ways of specifying the entry point.
+@kindex --exclude-libs
+@item --exclude-libs @var{lib},@var{lib},...
+Specifies a list of archive libraries from which symbols should not be automatically
+exported. The library names may be delimited by commas or colons. Specifying
+@code{--exclude-libs ALL} excludes symbols in all archive libraries from
+automatic export. This option is available only for the i386 PE targeted
+port of the linker and for ELF targeted ports. For i386 PE, symbols
+explicitly listed in a .def file are still exported, regardless of this
+option. For ELF targeted ports, symbols affected by this option will
+be treated as hidden.
+
@cindex dynamic symbol table
@kindex -E
@kindex --export-dynamic
for libraries that satisfy some reference from regular objects.
@option{--no-as-needed} restores the default behaviour.
+@kindex --add-needed
+@kindex --no-add-needed
+@item --add-needed
+@itemx --no-add-needed
+This option affects the treatment of dynamic libraries from ELF
+DT_NEEDED tags in dynamic libraries mentioned on the command line after
+the @option{--no-add-needed} option. Normally, the linker will add
+a DT_NEEDED tag for each dynamic library from DT_NEEDED tags.
+@option{--no-add-needed} causes DT_NEEDED tags will never be emitted
+for those libraries from DT_NEEDED tags. @option{--add-needed} restores
+the default behaviour.
+
@kindex -assert @var{keyword}
@item -assert @var{keyword}
This option is ignored for SunOS compatibility.
it. This option disallows symbols with undefined version and a fatal error
will be issued instead.
+@kindex --default-symver
+@item --default-symver
+Create and use a default symbol version (the soname) for unversioned
+exported symbols.
+
+@kindex --default-imported-symver
+@item --default-imported-symver
+Create and use a default symbol version (the soname) for unversioned
+imported symbols.
+
@kindex --no-warn-mismatch
@item --no-warn-mismatch
Normally @command{ld} will give an error if you try to link together input
@ifset XTENSA
@xref{Xtensa,, @command{ld} and Xtensa Processors}.
@end ifset
+@ifset M68HC11
+@xref{M68HC11/68HC12,,@command{ld} and the 68HC11 and 68HC12}.
+@end ifset
On some platforms, the @samp{--relax} option performs global
optimizations that become possible when the linker resolves addressing
everything else. This is to prevent gaps between symbols due to
alignment constraints.
+@kindex --sort-section name
+@item --sort-section name
+This option will apply @code{SORT_BY_NAME} to all wildcard section
+patterns in the linker script.
+
+@kindex --sort-section alignment
+@item --sort-section alignment
+This option will apply @code{SORT_BY_ALIGNMENT} to all wildcard section
+patterns in the linker script.
+
@kindex --split-by-file
@item --split-by-file [@var{size}]
Similar to @option{--split-by-reloc} but creates a new output section for
is, if the @code{SECTIONS} command does not specify a start address for
the section (@pxref{SECTIONS}).
+@kindex --warn-shared-textrel
+@item --warn-shared-textrel
+Warn if the linker adds a DT_TEXTREL to a shared object.
+
@kindex --warn-unresolved-symbols
@item --warn-unresolved-symbols
If the linker is going to report an unresolved symbol (see the option
exported. The symbol names may be delimited by commas or colons.
[This option is specific to the i386 PE targeted port of the linker]
-@kindex --exclude-libs
-@item --exclude-libs @var{lib},@var{lib},...
-Specifies a list of archive libraries from which symbols should not be automatically
-exported. The library names may be delimited by commas or colons. Specifying
-@code{--exclude-libs ALL} excludes symbols in all archive libraries from
-automatic export. Symbols explicitly listed in a .def file are still exported,
-regardless of this option.
-[This option is specific to the i386 PE targeted port of the linker]
-
@kindex --file-alignment
@item --file-alignment
Specify the file alignment. Sections in the file will always begin at
@c man end
+@ifset M68HC11
+@subsection Options specific to Motorola 68HC11 and 68HC12 targets
+
+@c man begin OPTIONS
+
+The 68HC11 and 68HC12 linkers support specific options to control the
+memory bank switching mapping and trampoline code generation.
+
+@table @gcctabopt
+
+@kindex --no-trampoline
+@item --no-trampoline
+This option disables the generation of trampoline. By default a trampoline
+is generated for each far function which is called using a @code{jsr}
+instruction (this happens when a pointer to a far function is taken).
+
+@kindex --bank-window
+@item --bank-window @var{name}
+This option indicates to the linker the name of the memory region in
+the @samp{MEMORY} specification that describes the memory bank window.
+The definition of such region is then used by the linker to compute
+paging and addresses within the memory window.
+
+@end table
+
+@c man end
+@end ifset
+
@ifset UsesEnvVars
@node Environment
@section Environment Variables
.data1 : @{ data.o(.data) @}
@end smallexample
-@cindex SORT
+@cindex SORT_BY_NAME
Normally, the linker will place files and sections matched by wildcards
in the order in which they are seen during the link. You can change
-this by using the @code{SORT} keyword, which appears before a wildcard
-pattern in parentheses (e.g., @code{SORT(.text*)}). When the
-@code{SORT} keyword is used, the linker will sort the files or sections
+this by using the @code{SORT_BY_NAME} keyword, which appears before a wildcard
+pattern in parentheses (e.g., @code{SORT_BY_NAME(.text*)}). When the
+@code{SORT_BY_NAME} keyword is used, the linker will sort the files or sections
into ascending order by name before placing them in the output file.
+@cindex SORT_BY_ALIGNMENT
+@code{SORT_BY_ALIGNMENT} is very similar to @code{SORT_BY_NAME}. The
+difference is @code{SORT_BY_ALIGNMENT} will sort sections into
+ascending order by alignment before placing them in the output file.
+
+@cindex SORT
+@code{SORT} is an alias for @code{SORT_BY_NAME}.
+
+When there are nested section sorting commands in linker script, there
+can be at most 1 level of nesting for section sorting commands.
+
+@enumerate
+@item
+@code{SORT_BY_NAME} (@code{SORT_BY_ALIGNMENT} (wildcard section pattern)).
+It will sort the input sections by name first, then by alignment if 2
+sections have the same name.
+@item
+@code{SORT_BY_ALIGNMENT} (@code{SORT_BY_NAME} (wildcard section pattern)).
+It will sort the input sections by alignment first, then by name if 2
+sections have the same alignment.
+@item
+@code{SORT_BY_NAME} (@code{SORT_BY_NAME} (wildcard section pattern)) is
+treated the same as @code{SORT_BY_NAME} (wildcard section pattern).
+@item
+@code{SORT_BY_ALIGNMENT} (@code{SORT_BY_ALIGNMENT} (wildcard section pattern))
+is treated the same as @code{SORT_BY_ALIGNMENT} (wildcard section pattern).
+@item
+All other nested section sorting commands are invalid.
+@end enumerate
+
+When both command line section sorting option and linker script
+section sorting command are used, section sorting command always
+takes precedence over the command line option.
+
+If the section sorting command in linker script isn't nested, the
+command line option will make the section sorting command to be
+treated as nested sorting command.
+
+@enumerate
+@item
+@code{SORT_BY_NAME} (wildcard section pattern ) with
+@option{--sort-sections alignment} is equivalent to
+@code{SORT_BY_NAME} (@code{SORT_BY_ALIGNMENT} (wildcard section pattern)).
+@item
+@code{SORT_BY_ALIGNMENT} (wildcard section pattern) with
+@option{--sort-section name} is equivalent to
+@code{SORT_BY_ALIGNMENT} (@code{SORT_BY_NAME} (wildcard section pattern)).
+@end enumerate
+
+If the section sorting command in linker script is nested, the
+command line option will be ignored.
+
If you ever get confused about where input sections are going, use the
@samp{-M} linker option to generate a map file. The map file shows
precisely how input sections are mapped to output sections.
it is often useful to mark sections that should not be eliminated.
This is accomplished by surrounding an input section's wildcard entry
with @code{KEEP()}, as in @code{KEEP(*(.init))} or
-@code{KEEP(SORT(*)(.ctors))}.
+@code{KEEP(SORT_BY_NAME(*)(.ctors))}.
@node Input Section Example
@subsubsection Input Section Example
which provides some control over the order in which global constructors
are run, you must sort the constructors at link time to ensure that they
are executed in the correct order. When using the @code{CONSTRUCTORS}
-command, use @samp{SORT(CONSTRUCTORS)} instead. When using the
-@code{.ctors} and @code{.dtors} sections, use @samp{*(SORT(.ctors))} and
-@samp{*(SORT(.dtors))} instead of just @samp{*(.ctors)} and
+command, use @samp{SORT_BY_NAME(CONSTRUCTORS)} instead. When using the
+@code{.ctors} and @code{.dtors} sections, use @samp{*(SORT_BY_NAME(.ctors))} and
+@samp{*(SORT_BY_NAME(.dtors))} instead of just @samp{*(.ctors)} and
@samp{*(.dtors)}.
Normally the compiler and linker will handle these issues automatically,
. = DATA_SEGMENT_END(.);
@end smallexample
+@item DATA_SEGMENT_RELRO_END(@var{offset}, @var{exp})
+@kindex DATA_SEGMENT_RELRO_END(@var{offset}, @var{exp})
+This defines the end of the @code{PT_GNU_RELRO} segment when
+@samp{-z relro} option is used. Second argument is returned.
+When @samp{-z relro} option is not present, @code{DATA_SEGMENT_RELRO_END}
+does nothing, otherwise @code{DATA_SEGMENT_ALIGN} is padded so that
+@var{exp} + @var{offset} is aligned to the most commonly used page
+boundary for particular target. If present in the linker script,
+it must always come in between @code{DATA_SEGMENT_ALIGN} and
+@code{DATA_SEGMENT_END}.
+
+@smallexample
+ . = DATA_SEGMENT_RELRO_END(24, .);
+@end smallexample
+
@item DEFINED(@var{symbol})
@kindex DEFINED(@var{symbol})
@cindex symbol defaults
use the @code{MEMORY} command to define discontinuous memory for the
output file, the two functions are equivalent.
+@item SEGMENT_START(@var{segment}, @var{default})
+@kindex SEGMENT_START(@var{segment}, @var{default})
+Return the base address of the named @var{segment}. If an explicit
+value has been given for this segment (with a command-line @samp{-T}
+option) that value will be returned; otherwise the value will be
+@var{default}. At present, the @samp{-T} command-line option can only
+be used to set the base address for the ``text'', ``data'', and
+``bss'' sections, but you use @code{SEGMENT_START} with any segment
+name.
+
@item SIZEOF(@var{section})
@kindex SIZEOF(@var{section})
@cindex section size
@ifset MSP430
* MSP430:: @command{ld} and MSP430
@end ifset
+@ifset M68HC11
+* M68HC11/68HC12:: @code{ld} and the Motorola 68HC11 and 68HC12 families
+@end ifset
@ifset TICOFF
* TI COFF:: @command{ld} and TI COFF
@end ifset
@raisesections
@end ifclear
+@ifset M68HC11
+@ifclear GENERIC
+@raisesections
+@end ifclear
+
+@node M68HC11/68HC12
+@section @command{ld} and the Motorola 68HC11 and 68HC12 families
+
+@cindex M68HC11 and 68HC12 support
+
+@subsection Linker Relaxation
+
+For the Motorola 68HC11, @command{ld} can perform these global
+optimizations when you specify the @samp{--relax} command-line option.
+
+@table @emph
+@cindex relaxing on M68HC11
+@item relaxing address modes
+@command{ld} finds all @code{jsr} and @code{jmp} instructions whose
+targets are within eight bits, and turns them into eight-bit
+program-counter relative @code{bsr} and @code{bra} instructions,
+respectively.
+
+@command{ld} also looks at all 16-bit extended addressing modes and
+transforms them in a direct addressing mode when the address is in
+page 0 (between 0 and 0x0ff).
+
+@item relaxing gcc instruction group
+When @command{gcc} is called with @option{-mrelax}, it can emit group
+of instructions that the linker can optimize to use a 68HC11 direct
+addressing mode. These instructions consists of @code{bclr} or
+@code{bset} instructions.
+
+@end table
+
+@subsection Trampoline Generation
+
+@cindex trampoline generation on M68HC11
+@cindex trampoline generation on M68HC12
+For 68HC11 and 68HC12, @command{ld} can generate trampoline code to
+call a far function using a normal @code{jsr} instruction. The linker
+will also change the relocation to some far function to use the
+trampoline address instead of the function address. This is typically the
+case when a pointer to a function is taken. The pointer will in fact
+point to the function trampoline.
+
+@ifclear GENERIC
+@lowersections
+@end ifclear
+@end ifset
+
@node ARM
-@section @command{ld}'s Support for Interworking Between ARM and Thumb Code
+@section @command{ld} and the ARM family
@cindex ARM interworking support
@kindex --support-old-code
executables. This option is only valid when linking big-endian objects.
The resulting image will contain big-endian data and little-endian code.
+@cindex TARGET1
+@kindex --target1-rel
+@kindex --target1-abs
+The @samp{R_ARM_TARGET1} relocation is typically used for entries in the
+@samp{.init_array} section. It is interpreted as either @samp{R_ARM_REL32}
+or @samp{R_ARM_ABS32}, depending on the target. The @samp{--target1-rel}
+and @samp{--target1-abs} switches override the default.
+
+@cindex TARGET2
+@kindex --target2=@var{type}
+The @samp{--target2=type} switch overrides the default definition of the
+@samp{R_ARM_TARGET2} relocation. Valid values for @samp{type}, their
+meanings, and target defaults are as follows:
+@table @samp
+@item rel
+@samp{R_ARM_REL32} (arm*-*-elf, arm*-*-eabi)
+@item abs
+@samp{R_ARM_ABS32} (arm*-*-symbianelf)
+@item got-rel
+@samp{R_ARM_GOT_PREL} (arm*-*-linux, arm*-*-*bsd)
+@end table
+
@ifclear GENERIC
@lowersections
@end ifclear
the original names for the renamed symbols will be exported.
In effect, you'd be aliasing those symbols, not renaming them,
which is probably not what you wanted.
+
+@cindex weak externals
+@item weak externals
+The Windows object format, PE, specifies a form of weak symbols called
+weak externals. When a weak symbol is linked and the symbol is not
+defined, the weak symbol becomes an alias for some other symbol. There
+are three variants of weak externals:
+@itemize
+@item Definition is searched for in objects and libraries, historically
+called lazy externals.
+@item Definition is searched for only in other objects, not in libraries.
+This form is not presently implemented.
+@item No search; the symbol is an alias. This form is not presently
+implemented.
+@end itemize
+As a GNU extension, weak symbols that do not specify an alternate symbol
+are supported. If the symbol is undefined when linking, the symbol
+uses a default value.
@end table
@ifclear GENERIC
group of files followed by the @code{.text} sections of that group of
files. Then, the @code{.literal} sections from the rest of the files
and the @code{.text} sections from the rest of the files would follow.
-The non-interleaved order can still be specified as:
-
-@smallexample
-SECTIONS
-@{
- .text : @{
- *(.literal) *(.text)
- @}
-@}
-@end smallexample
-@cindex @code{--relax} on Xtensa
+@cindex @option{--relax} on Xtensa
@cindex relaxing on Xtensa
+Relaxation is enabled by default for the Xtensa version of @command{ld} and
+provides two important link-time optimizations. The first optimization
+is to combine identical literal values to reduce code size. A redundant
+literal will be removed and all the @code{L32R} instructions that use it
+will be changed to reference an identical literal, as long as the
+location of the replacement literal is within the offset range of all
+the @code{L32R} instructions. The second optimization is to remove
+unnecessary overhead from assembler-generated ``longcall'' sequences of
+@code{L32R}/@code{CALLX@var{n}} when the target functions are within
+range of direct @code{CALL@var{n}} instructions.
+
+For each of these cases where an indirect call sequence can be optimized
+to a direct call, the linker will change the @code{CALLX@var{n}}
+instruction to a @code{CALL@var{n}} instruction, remove the @code{L32R}
+instruction, and remove the literal referenced by the @code{L32R}
+instruction if it is not used for anything else. Removing the
+@code{L32R} instruction always reduces code size but can potentially
+hurt performance by changing the alignment of subsequent branch targets.
+By default, the linker will always preserve alignments, either by
+switching some instructions between 24-bit encodings and the equivalent
+density instructions or by inserting a no-op in place of the @code{L32R}
+instruction that was removed. If code size is more important than
+performance, the @option{--size-opt} option can be used to prevent the
+linker from widening density instructions or inserting no-ops, except in
+a few cases where no-ops are required for correctness.
+
+The following Xtensa-specific command-line options can be used to
+control the linker:
+
+@cindex Xtensa options
+@table @option
@kindex --no-relax
-The Xtensa version of @command{ld} enables the @option{--relax} option by
-default to attempt to reduce space in the output image by combining
-literals with identical values. It also provides the
-@option{--no-relax} option to disable this optimization. When enabled,
-the relaxation algorithm ensures that a literal will only be merged with
-another literal when the new merged literal location is within the
-offset range of all of its uses.
-
-The relaxation mechanism will also attempt to optimize
-assembler-generated ``longcall'' sequences of
-@code{L32R}/@code{CALLX@var{n}} when the target is known to fit into a
-@code{CALL@var{n}} instruction encoding. The current optimization
-converts the sequence into @code{NOP}/@code{CALL@var{n}} and removes the
-literal referenced by the @code{L32R} instruction.
+@item --no-relax
+Since the Xtensa version of @code{ld} enables the @option{--relax} option
+by default, the @option{--no-relax} option is provided to disable
+relaxation.
+
+@item --size-opt
+When optimizing indirect calls to direct calls, optimize for code size
+more than performance. With this option, the linker will not insert
+no-ops or widen density instructions to preserve branch target
+alignment. There may still be some cases where no-ops are required to
+preserve the correctness of the code.
+@end table
@ifclear GENERIC
@lowersections
projects / deliverable / binutils-gdb.git / blobdiff