view doc/scripts.txt @ 140:8d65ef71fc01

repo reorg
author lost
date Wed, 28 Jan 2009 06:00:48 +0000
parents 106c2fe3c9d9
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LWLINK linker scripts

A linker script is used to instruct the linker about how to assemble the
various sections into a completed binary. It consists of a series of
directives which are considered in the order they are encountered. Any
section not referenced by a directive is assumed to be loaded after the
final section explicitly referenced.

The sections will appear in the resulting binary in the order they are
specified in the script file.

If a referenced section is not found, the linker will behave as though the
section did exist but had a zero size, no relocations, and no exports.

A section may only be referenced once. Any subsequent references will have
no effect.

All numbers are hexadecimal.

section <name> load <addr>

This causes the section <name> to load at <addr>. For raw target, only one
"load at" entry is allowed for non-bss sections and it must be the first
one. For raw targets, it affects the addresses the linker assigns to symbols
but has no other affect on the output. bss sections may all have separate
load addresses but since they will not appear in the binary anyway, this is
okay.

For the DECB target, each "load" entry will cause a new "block" to be
output to the binary which will contain the load address. It is legal for
sections to overlap in this manner - the linker assumes the loader will sort
everything out.

section <name>

This will cause the section <name> to load after the previously listed
section.

exec <addr or sym>

This will cause the execution address (entry point) to be the address
specified (in hex) *or* the specified symbol name. The symbol name must
match a symbol that is exported by one of the object files being linked.
This has no effect for targets that do not encode the entry point into the
resulting file. If not specified, the entry point is assumed to be address 0
which is probably not what you want. The default link scripts for targets
that support this directive automatically starts at the beginning of the
first section (usually "init" or "code") that is emitted in the binary.

pad <size>

This will cause the output file to be padded with NUL bytes to be exactly
<size> bytes in length. This only makes sense for a raw target.


If <name> is "*", then any section not already matched by the script will be
matched. For format *,<flags> can be used to select sections which have
particular flags set (or not set). For instance:

*,!bss		This would match all sections that do not have the bss flag set
*,bss		this would match all sections that do have the bss flag set