Difference between revisions of "Placing external library symbols at specific address"

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(Created page with "One of the big benefits of the SEGGER Linker is its simple usage. In this scenario an external library will be placed in a specific memory location. * Usually everything is pl...")
 
 
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One of the big benefits of the SEGGER Linker is its simple usage. In this scenario an external library will be placed in a specific memory location.
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One of the big benefits of the SEGGER Linker is its simple usage.  
* Usually everything is placed under .text section. Check your symbol browser or map file to locate how the subsection of the external library is called. For this example we will show how the libc library can be placed into a different Flash memory region.
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In this scenario an external library will be placed in a specific memory location.
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* Usually everything is placed under .text section. Check your symbol browser or map file to locate how the subsection of the external library is called. For this example we will show how the libc library can be placed into a different memory region.
 
* Open your projects linker script(.icf file) for editing.
 
* Open your projects linker script(.icf file) for editing.
* Make sure the memory regions you are looking to use are defined in your memory map file or in project settings in memory segments. e.g.
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* Add a new placement for your particular library subsection into the desired region. e.g.
<pre>define region FLASH    = FLASH1;
 
define region FLASH_LIB = FLASH2;</pre>
 
* Add a new Flash placement for your particular library subsection e.g.
 
 
<pre>
 
<pre>
place in FLASH_LIB                          { section .text.libc, section .text.libc.*};
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place in MEM_LIB                            { section .text.libc, section .text.libc.*};
 
</pre>
 
</pre>
* In the general .text Flash placement add an exception for this subsection otherwise the linker will throw an error that the same symbols are linked twice.
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* In the general placement where other code sections are placed, add an exception for this subsection otherwise the linker will throw an error that the same symbols are linked twice.
 
<pre>
 
<pre>
 
place in FLASH with minimum size order      { section .init,  section .init.*,        // Init code section
 
place in FLASH with minimum size order      { section .init,  section .init.*,        // Init code section
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                                     except { section .text.libc, section .text.libc.*};
 
                                     except { section .text.libc, section .text.libc.*};
 
</pre>
 
</pre>
* Now everything should be set up and all libc function should be linked into region FLASH2
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* Now everything should be set up and all libc function should be linked into region MEM_LIB.

Latest revision as of 14:40, 14 January 2020

One of the big benefits of the SEGGER Linker is its simple usage. In this scenario an external library will be placed in a specific memory location.

  • Usually everything is placed under .text section. Check your symbol browser or map file to locate how the subsection of the external library is called. For this example we will show how the libc library can be placed into a different memory region.
  • Open your projects linker script(.icf file) for editing.
  • Add a new placement for your particular library subsection into the desired region. e.g.
place in MEM_LIB                            { section .text.libc, section .text.libc.*};
  • In the general placement where other code sections are placed, add an exception for this subsection otherwise the linker will throw an error that the same symbols are linked twice.
place in FLASH with minimum size order      { section .init,   section .init.*,        // Init code section
                                              section .init_rodata, section .init_rodata.*, // Init read-only section
                                              section .text,   section .text.*,        // Code section
                                              section .rodata, section .rodata.*,      // Read-only data section
                                              section .segger.*,                       // Auto-generated initialization
                                              block exidx,                             // ARM exception unwinding block
                                              block ctors,                             // Constructors block
                                              block dtors }                            // Destructors block
                                     except { section .text.libc, section .text.libc.*};
  • Now everything should be set up and all libc function should be linked into region MEM_LIB.