STM32CubeMX with MMT: strange LD file generation

[FluxPower42]

STM32CubeMX v6.17.0

While configuring an STM32CubeMX project for an STM32H753 Ethernet project on a NUCLEO-H753ZI, I observed some strange behavior.

After enabling memory management, including the checkboxes
- Apply Application Regions Settings to Peripherals and
- Apply Application Regions Settings to Linker Files,
I would have expected the memory regions to be included in the linker description file STM32H753XX_FLASH.ld.

Unfortunately, this was not the case.

However, since the STM32H753XX_FLASH.ld file had obviously been regenerated, I did not suspect the file handling itself.
After several hours of searching, I discovered that if the .ld file is deleted before regeneration, different content is generated.

Steps to reproduce this:

1. Open STM32CubeMX
2. File / New Project… / Board Selector
3. Select NUCLEO-H753ZI
4. In „Board Project Options“ dialog, click button „Unselect All“
5. Set Project Manager / Project / Toolchain / IDE  to CMake
   and Default Compiler/Linker to ST Arm Clang
6. File / Save Project
7. Generate Code
8. Check the file size of STM32H753XX_FLASH.ld file (in my case: 8671 Bytes)
9. Make a *copy* of the STM32H753XX_FLASH.ld file to STM32H753XX_FLASH_01.ld for later compare, but don't delete the file.
   
   
10. In STM32CubeMX Go to Tools / Memory Management
    - Switch Apply Application Regions Settings to Peripherals On
    - Switch Apply Application Regions Settings to Linker Files On
11. File / Save Project
12. Generate Code
13. Check the file size of STM32H753XX_FLASH.ld file (in my case: 8651 Bytes)
14. Make a *copy* of the STM32H753XX_FLASH.ld file to STM32H753XX_FLASH_02.ld
15. Compare the file _01.ld file from step 9 with this _02.ld file:
    
    
    
16. *Delete* the STM32H753XX_FLASH.ld
17. Generate Code again and open STM32H753XX_FLASH.ld file again
18. Check the file size of STM32H753XX_FLASH.ld file (in my case: 9119 Bytes)
19. Make a *copy* of the STM32H753XX_FLASH.ld file to STM32H753XX_FLASH_03.ld
20. Compare the file _01.ld file from step 9 with this _03.ld file:
    

    [...]

    

    [...]
    
    

    
    

     

The regions are now available.
However, according to the comment header, the controller has now much more flash memory, but zero RAM :)


In addition, when the STM32CubeMX GUI is started with command line logging, two warnings occur during code generation after the MMT tab is opened once:

2026-04-23 19:59:33,111 [INFO] CodeEngine:319 - Generated code: D:\dev\Prj\CubeMXTest\CubeMXTest\MXTmpFiles\gpio.tmp
2026-04-23 19:59:33,121 [WARN] IPConfigManager:107 - WARNING: Missing Config File for MEMORYMAP ip!!
2026-04-23 19:59:33,122 [WARN] IP:2258 - DefaultDataRegion not found: check if there is a RefParameter without a condition.
2026-04-23 19:59:33,153 [INFO] CodeEngine:295 - oldGeneratedFile, D:\dev\Prj\CubeMXTest\CubeMXTest\MXTmpFiles\cortex.tmp_save

If you click on the RAM_D2 (or other) table cell now and regenerate it without changing the content, the error "IP:2258 - DefaultDataRegion not found" will disappear:

2026-04-23 20:00:00,152 [INFO] CodeEngine:319 - Generated code: D:\dev\Prj\CubeMXTest\CubeMXTest\MXTmpFiles\gpio.tmp
2026-04-23 20:00:00,161 [WARN] IPConfigManager:107 - WARNING: Missing Config File for MEMORYMAP ip!!
2026-04-23 20:00:00,191 [INFO] CodeEngine:295 - oldGeneratedFile, D:\dev\Prj\CubeMXTest\CubeMXTest\MXTmpFiles\cortex.tmp_save

The next behavior occurs if the ETH module is switched on (to RMII) after the MMT is still activated.
The error appears in the MMT output log:

However, if you switch to Tools / Memory Management, the output view is disabled.
When you turn it back on, the content is empty:

until you switch the ETH off and on again, you will see both the new and old errors:

I have a feeling that this feature is in a very beta state (or perhaps it's very KI-generated?)
ST: Thank you for fixing and testing the tool - I'm already excited for the new version!

Best wishes, Timo

[Souhaib MAZHOUD]

Hello @FluxPower42 

Could you please attach your ioc in order to investigate the issue?

BR, Souhaib

[FluxPower42]

@Souhaib MAZHOUD 

the steps to generate the .ioc file in the different states are described in my post.
To make it easy for you: attached a zip with folders of the different steps (note that the index numbers of the folders are different to the numbers in my post).
In this zip you will find the .ioc files on the journey and and all files that have been modified during generation steps.

Please keep in mind, that you have to start without active MMT. Then generate the code (and the ld file). Then switch MMT and "Apply Application Regions Settings to Linker Files" on. Generate and check the ld file. Delete the file, generate again and check the ld file again.

Best wishes,
Timo