.bss section is loaded from FLASH

[martin2250]

My recent project is filling up the flash and I got this error message, which made the compilation fail

= note: rust-lld: error: section '.bss' will not fit in region 'FLASH': overflowed by 1284 bytes

That got me wondering, usually the .bss section is initialized with zeroes so there is no need to put it into flash. Here is the offending entry in the generated link.x from qingke-rt:

    .bss : ALIGN(4)
    {
        PROVIDE( _sbss = .);
        *(.sbss .sbss.* .bss .bss.*);
        PROVIDE( _ebss = .);
    } >RAM AT>FLASH

Instead, I'd expect something more along the lines of this (generated by cortex-m-rt:

  /* ### .bss */
  .bss (NOLOAD) : ALIGN(4)
  {
    . = ALIGN(4);
    __sbss = .;
    *(.bss .bss.*);
    *(COMMON); /* Uninitialized C statics */
    . = ALIGN(4); /* 4-byte align the end (VMA) of this section */
  } > RAM

Depending on the size of .bss, the binary size could be reduced significantly by switching to a similar linker script.

Is there a reasoning behind the decision to load .bss from flash or was a proper zeroing routine simply not yet implemented?