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doc: reloacation: shorten long lines

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Some style fixes and change title.

Signed-off-by: Anas Nashif <anas.nashif@intel.com>
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Anas Nashif 2019-01-05 12:21:02 -05:00
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doc/tools/code-relocation.rst
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@ -1,19 +1,18 @@
.. _code_data_relocation:
Code data relocation
####################
Code And Data Relocation
########################
Overview
********
This script will relocate .text, .rodata, .data, and .bss sections from
required files and place them in the required memory region. The
memory region and file are given to this python script in the form
of a string. This script is always invoked from inside cmake.
This feature will allow relocating .text, .rodata, .data, and .bss sections from
required files and place them in the required memory region. The memory region
and file are given to this python script in the form of a string. This script is
always invoked from inside cmake.
This script provides a robust way to re-order
the memory contents without actually having to modify the code.
In simple terms this script will do the job of
``__attribute__((section("name")))`` for a bunch of files together.
This script provides a robust way to re-order the memory contents without
actually having to modify the code. In simple terms this script will do the job
of ``__attribute__((section("name")))`` for a bunch of files together.
Details
*******
@ -25,20 +24,23 @@ An example of such a string is:
This script is invoked with the following parameters:
``python3 gen_relocate_app.py -i input_string -o generated_linker -c generated_code``
Kconfig :option:`CONFIG_CODE_DATA_RELOCATION` option, when enabled in ``prj.conf``, will
invoke the script and do the required relocation.
Kconfig :option:`CONFIG_CODE_DATA_RELOCATION` option, when enabled in
``prj.conf``, will invoke the script and do the required relocation.
This script also trigger the generation of ``linker_relocate.ld`` and ``code_relocation.c`` files.
The ``linker_relocate.ld`` file creates appropriate sections and
links the required functions or variables from all the selected files.
This script also trigger the generation of ``linker_relocate.ld`` and
``code_relocation.c`` files. The ``linker_relocate.ld`` file creates
appropriate sections and links the required functions or variables from all the
selected files.
**Note**:
The text section is split into 2 parts in the main linker script. The first section
will have some info regarding vector tables and other debug related info.
The second section will have the complete text section.
This is needed to force the required functions and data variables to the correct locations.
This is due to the behavior of the linker. The linker will only link once and
hence this text section had to be split to make room for the generated linker script.
.. note::
The text section is split into 2 parts in the main linker script. The first
section will have some info regarding vector tables and other debug related
info. The second section will have the complete text section. This is
needed to force the required functions and data variables to the correct
locations. This is due to the behavior of the linker. The linker will only
link once and hence this text section had to be split to make room for the
generated linker script.
The ``code_relocation.c`` file has code that is needed for
initializing data sections, and a copy of the text sections (if XIP).
@ -57,18 +59,20 @@ for data copy operations from ROM to required memory type.
Where the first argument is the file/files and the second
argument is the memory where it must be placed.
.. note::
The file argument supports limited regular expressions.
function zephyr_code_relocate() can be called as many times as required.
This step has to be performed before the inclusion of boilerplate.cmake.
.. note::
The file argument supports limited regular expressions.
function zephyr_code_relocate() can be called as many times as required.
This step has to be performed before the inclusion of boilerplate.cmake.
Additional Configurations
=========================
This section shows additional configuration options that can be set in ``CMakeLists.txt``
This section shows additional configuration options that can be set in
``CMakeLists.txt``
* if the memory is SRAM1, SRAM2, CCD, or AON, then place the full object in the sections
for example:
* if the memory is SRAM1, SRAM2, CCD, or AON, then place the full object in the
sections for example:
.. code-block:: none
@ -93,5 +97,6 @@ A sample showcasing this feature is provided at
``$ZEPHYR_BASE/samples/test_relocation/``
This is an example of using the code relocation feature.
This example will place .text, .data, .bss from 3 files to various parts in the SRAM
using a custom linker file derived from ``include/arch/arm/cortex_m/scripts/linker.ld``