Compiled code size and flashed code size are different in STM32CUBEIDE v1.15.1

[Simo_Sappo]

Hi everyone, I created an HID bootloader for the STM32G4xxx, it works and now I am trying to optimize the size. After compiling I can read this on the Build Analyzer a flash memory usage of 17.85 kB. 

After compiling I get this:

 

When I flash this compiled code and read the flash memory I canclearly see that the memory usage is around 38 kB.  

I also used the STM32CubeProgrammer to look at the actual memory (I didn't manage to use this function directly on STM32CubeIDE) and I can see that more than 38 kB are used in the memory

Can somebody explain why? Am I missing something about the Build Analyzer function?

 

[gbm]

SREC file is a text file. It's size is a little over 2 times the programmed Flash footprint.

[Simo_Sappo]

Thank you very much, is there a way to reduce its size or to flash into memory a different file that woul dbe smaller?

[Andrew Neil]

What's programmed into Flash is more than just the code - there's also all the data initialisation values.

The Build Analyser shows you exactly what's going into the Flash, and where:

 

 

Everything in the 'Load address' column is stored in Flash

.text is your executable code; some of the other things are mentioned here:

https://stackoverflow.com/questions/15265295/understanding-the-libc-init-array 

 

 

[Simo_Sappo]

My problem is that the code I am actually flashing in the microcontroller is 38.37 kB, which I confirmed by also opening the flash memory with STM32CubeProgrammer. I don't understand why I am flashing a file that is double the size of my actual code.

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[Andrew Neil]

But, as @gbm already said, that's the size of  the SREC file on your hard drive - not the size of the data which gets programmed into the Flash?

[Simo_Sappo]

Yes, but as I said I looked in the flash memory with  the STM32 Programmer, and as you can also see I have code until 0x08009974, which is page 19 of the Flash memory. So the actual occupied memory size is more than 38 kB (each page is 2 kB in dual bank mode). 

 

Edit: I said single bank mode but I meant dual bank mode)

[Simo_Sappo]

Nope, until 0x08009974 there are no gaps, no "FFFF" is written before the one you see in the picture. I checked

[Simo_Sappo]

I found the problem, somehow even if I set the Release mode as active (with the size optimization) it was still flashing the Debug version of the code which is not optimized for size. I discovered this only after deleting the Debug and Release folders and staring the flashing process again. Thank you everyone for your help

[Andrew Neil]

Switching between Release and Debug (or other) Configurations does not change the Debug Configuration.

Same issue here:

https://community.st.com/t5/stm32cubeide-mcus/build-analyzer-underestimates-by-30-flash-memory-usage/m-p/819739/highlight/true#M37233