1 .section ".text.boot"
2 
3 .global _start
4 _start:
5     mrs     x0, mpidr_el1
6     and     x0, x0, #0xffffff
7     cbz     x0, _first_processor
8 
9     // hang all non primary CPU
10 _idle:
11     wfe
12     b       _idle
13 
14 _first_processor:
15     // zero out BSS section
16     adr     x0, bss_begin
17     adr     x1, bss_end
18 _zero_bss:
19     str     xzr, [x0], #8
20     cmp     x0, x1
21     b.lt    _zero_bss
22 
23     # set stack before boot code and call kernel
24     adr     x0, _start
25     mov     sp, x0
26     bl      kernel_entry_point
27     b       _idle