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

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Revision as of 14:35, 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 Flash memory region.
  • 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.
define region FLASH     = FLASH1;
define region FLASH_LIB = FLASH2;
  • Add a new Flash placement for your particular library subsection e.g.
place in FLASH_LIB                          { section .text.libc, section .text.libc.*};
  • 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.
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 FLASH2