Microcontrollers - memory sections

The .text section contains the actual machine instructions which make up your program.

Uninitialized global or static variables end up in the .bss section.

In computing, a data segment (often denoted .data) is a portion of an object file or the corresponding virtual address space of a program that contains initialized static variables.

The heap area commonly begins at the end of the .bss and .data segments and grows to larger addresses from there. The heap area is managed by malloc, realloc, and free.

The stack is the memory set aside as scratch space for a thread of execution. When a function is called, a block is reserved on the top of the stack for local variables and some bookkeeping data. When that function returns, the block becomes unused and can be used the next time a function is called.

A lot of embedded solution need of backup ram. The backup ram is a section of memory with an alternative supply voltage. To allocate variables in this section we need to use precompiler defines (#pragma section xxxx). The variables inside this section haven't to be initialized at the start of the program in case of backup ram is ok (this check can be done with crc).