See the top level README for information on where to find documentation
for the raspberry pi and the ARM processor inside. Also find information
on how to load and run these programs.
These examples are for the pi2, see other directories for other
flavors of raspberry pi. Specifically these examples are for running
in SVC mode. As of this writing the GPU planted bootstrap places
the ARM in HYP mode. For the moment I am using the code below to return
the ARM to SVC and secure mode. At least until it breaks.
The bootloader is one level up and shared for both SVC and HYP as I
want the applications loaded to make the changes not the bootloader.
.globl _start
_start:
ldr pc,reset_handler
ldr pc,undefined_handler
ldr pc,swi_handler
ldr pc,prefetch_handler
ldr pc,data_handler
ldr pc,hyp_handler
ldr pc,irq_handler
ldr pc,fiq_handler
reset_handler: .word reset
undefined_handler: .word hang
swi_handler: .word smc
prefetch_handler: .word hang
data_handler: .word hang
hyp_handler: .word hang
irq_handler: .word hang
fiq_handler: .word hang
reset:
;@ b skip
mrs r0,cpsr
bic r0,r0,#0x1F
orr r0,r0,#0x13
msr spsr_cxsf,r0
add r0,pc,#4
msr ELR_hyp,r0
eret
skip:
mrc p15, 0, r1, c12, c0, 0 ;@ get vbar
mov r0,#0x8000
;@ mov r1,#0x0000
ldmia r0!,{r2,r3,r4,r5,r6,r7,r8,r9}
stmia r1!,{r2,r3,r4,r5,r6,r7,r8,r9}
ldmia r0!,{r2,r3,r4,r5,r6,r7,r8,r9}
stmia r1!,{r2,r3,r4,r5,r6,r7,r8,r9}
mov r12,#0
mcr p15, 0, r12, c7, c10, 1
dsb
mov r12, #0
mcr p15, 0, r12, c7, c5, 0
mov r12, #0
mcr p15, 0, r12, c7, c5, 6
dsb
isb
smc #0
mrc p15,0,r2,c1,c0,0
bic r2,#0x1000
bic r2,#0x0004
mcr p15,0,r2,c1,c0,0
mov sp,#0x8000
mov r0,pc
bl notmain
hang: b hang
smc:
mrc p15, 0, r1, c1, c1, 0
bic r1, r1, #1
mcr p15, 0, r1, c1, c1, 0
movs pc, lr
