Difference between revisions of "Placing external library symbols at specific address"
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+ | [[Category:Embedded Studio]] |
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+ | ==How to== |
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One of the big benefits of the SEGGER Linker is its simple usage. |
One of the big benefits of the SEGGER Linker is its simple usage. |
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In this scenario an external library will be placed in a specific memory location. |
In this scenario an external library will be placed in a specific memory location. |
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</pre> |
</pre> |
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* Now everything should be set up and all libc function should be linked into region MEM_LIB. |
* Now everything should be set up and all libc function should be linked into region MEM_LIB. |
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+ | '''Note:''' If you are placing the symbols in RAM the following must be considered additionally: |
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− | * To make sure this stays valid after a reset/reboot of the device the library functions must be initialized during startup by copying them from Flash to RAM. |
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+ | [https://wiki.segger.com/Functions_in_RAM Placing functions in RAM] |
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− | * This can be done by adding the following line to the remaining "initialize by copy entries". |
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+ | |||
− | <pre> |
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+ | ==Example project== |
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− | initialize by copy { section .text.libc, section .text.libc.* }; |
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+ | The following example project shows such a setup where the SEGGER Runtime Library functions are all linked into RAM. To verify the setup the IDE [https://www.segger.com/products/development-tools/embedded-studio/ Embedded Studio] can be used to rebuild and debug the project. |
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− | </pre> |
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+ | ===Prerequisites=== |
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+ | * Embedded Studio V4.50 or later |
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+ | * STM32F407VE based target board e.g. a [https://www.segger.com/products/debug-probes/j-trace/accessories/trace-reference-boards/overview/#cortex-m-trace-reference-board Cortex-M Trace Reference Board] |
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+ | * [https://www.segger.com/products/debug-probes/j-link/models/model-overview/ J-Link Base] V10 or higher |
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+ | |||
+ | ===Project=== |
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+ | [[Media:STM32F407VE_SEGGER_RunTimeLibrary_LinkToRAM.zip|STM32F407VE_SEGGER_RunTimeLibrary_LinkToRAM.zip]] |
Latest revision as of 17:07, 17 June 2020
How to
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.
Note: If you are placing the symbols in RAM the following must be considered additionally: Placing functions in RAM
Example project
The following example project shows such a setup where the SEGGER Runtime Library functions are all linked into RAM. To verify the setup the IDE Embedded Studio can be used to rebuild and debug the project.
Prerequisites
- Embedded Studio V4.50 or later
- STM32F407VE based target board e.g. a Cortex-M Trace Reference Board
- J-Link Base V10 or higher