topic Re: BSS section problems KDS3.0 with kv4x in Kinetis Design Studio

BSS section problems KDS3.0 with kv4x

robertozanichel — Fri, 10 Feb 2017 09:11:14 GMT

Good morning,

I've a problem related to linker allocation of memory sections, the linker keep putting variables in .bss memory section even if they are initialized and different from 0.

The #pragma section instruction on the arm site (that i've seen in a similar discussion) seems to have no effect.

COMPILER OUTPUT:

Invoking: Cross ARM C++ Linker

.....
..../kds_v3/toolchain/bin/../lib/gcc/arm-none-eabi/4.8.4/../../../../arm-none-eabi/bin/ld.exe: myelf.elf section `.bss' will not fit in region `m_data'
..../kds_v3/toolchain/bin/../lib/gcc/arm-none-eabi/4.8.4/../../../../arm-none-eabi/bin/ld.exe: region `m_data' overflowed by 92 bytes
collect2.exe: error: ld returned 1 exit status

i want to know if there is an effective and proved solution to avoid bss occupation because every global variable that i use has it's own initialization function that is called inside the code so i don't see the need of the compiler to do it before my initialization.

Thaks for help,

i hope you help me to clarify this.

Re: BSS section problems KDS3.0 with kv4x

Alice_Yang — Wed, 15 Feb 2017 03:59:41 GMT

Hello Roberto,

- The .bss contains all the uninitalized data.

text, data and bss: Code and Data Size Explained | MCU on Eclipse

- If the RAM overflowed, you can relocate the variable into flash , the detail steps

please refer to this DOC:

Relocating Code and Data Using the KDS GCC Linker File for Kinetis

Hope it helps

Have a great day,
Alice Yang

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Re: BSS section problems KDS3.0 with kv4x

robertozanichel — Thu, 16 Feb 2017 13:24:16 GMT

Thank you very much,

i was already confident with the first link you gave me, i knew that bss was where to put uninitalized data, and i think also the data intialized as zero goes there.
I took care of all the initialization but i think sometimes code optimization play me. I solved the problem simply reorganizing the code so there is still some "black magic" for me.

I was hoping to find a much easier (and portable) solution than using the section attribute, but i think there is "no free lunch", thanks for the link, i really missed that topic...

Anyway thanks for help!!! the topic helped me to have a deeper understanding.