I also think that might be sufficient. uncached data does not make a lot of sense and the zero initialization does not necesarilly have to happen before the main. I simply used 

```txt
SECTIONS
{
  /* Uncached memory */
  uncached (NOLOAD) : ALIGN(4) {
    . = ALIGN(4);
    _sbss_uncached = .;
    *(.bss.uncached .bss.uncached.*);
    . = ALIGN(4);
    _ebss_uncached = .;
  } > UNCACHED
}

 ```