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
|
# bootloader for my kernel
.option norvc
.section .data
.section .text.init
.global _start
_start:
# any harts not bootstrapping need to wait for an IPI
csrr t0, mhartid
bnez t0, 3f
# satp should be zero, but make sure
csrw satp, zero
.option push
.option norelax
la gp, __global_pointer$
.option pop
# clear bss
la a0, _bss_start
la a1, _bss_end
bgeu a0, a1, 2f
1:
sd zero, (a0)
addi a0, a0, 8
bltu a0, a1, 1b
2:
# set up stack
la sp, _stack_end
# set kmain to the return address and then return
li t0, (0b11 << 11) | (1 << 7) | (1 << 3)
la t1, kmain
la t2, asm_trap_vector
li t3, 0 # (1 << 3) | (1 << 7) | (1 << 11)
csrw mstatus, t0
csrw mepc, t1
csrw mtvec, t2
csrw mie, t3
mret
# wait for interrupt
3:
wfi
j 3b
|
