1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
|
// armv7 mode
// To keep this in the first portion of the binary.
.section ".text.boot"
//.org 0x8000
// Make _start global.
.globl _start
// Entry point for the kernel.
// r15 -> should begin execution at 0x8000.
// r0 -> 0x00000000
// r1 -> 0x00000C42
// r2 -> 0x00000100 - start of ATAGS
// preserve these registers as argument for kernel_main
_start:
// Shut off extra cores
mrc p15, 0, r5, c0, c0, 5
and r5, r5, #3
cmp r5, #0
bne halt
// Setup the stack.
// It shall be directly below our kernel image
ldr r5, =__start
mov sp, r5
// Clear out bss.
ldr r4, =__bss_start
ldr r9, =__bss_end
mov r5, #0
mov r6, #0
mov r7, #0
mov r8, #0
b 2f
1:
// store multiple at r4.
stmia r4!, {r5-r8}
// If we are still below bss_end, loop.
2:
cmp r4, r9
blo 1b
// Call kernel_main
ldr r3, =kernel_main
bx r3
// halt
halt:
wfe
b halt
|
