General Practices for clearing BSS segments

Link scripts generally contain similar statements:

_ Bss_start = .; __bss_start _ = .;. bss :{*(. shbss )*(. bss. bss. *. gnu. linkonce. b. *) * (COMMON )}. = ALIGN (4); _ bss_end = .; __bss_end _ = .;

The code for the startup process is generally compiled as follows:

@ ++ Clear the BSS section ++ ldr r2, =__ bss_start _ ldr r3, =__ bss_end _ mov r12, # 0bss_loop: cmp r2, r3 stmltia r2 !, {R12} blt bss_loop @ ---- clear the BSS section ----

Therefore, do not assign 0 to uninitialized global variables in the C code, because the BSS segment is automatically assigned 0.

This article is from "song Baohua's blog", please be sure to keep this source http://21cnbao.blog.51cto.com/109393/1295126