Problem jumping to supervisor mode

[Xavier Barreto Tomeo]

Hi, im working on my project but I have an issue still unsolved. I'm unable to jump to supervisor mode and I don't know why.

I'm going to paste my code and try to explain it and let's see if someone can help me asap haha! This is the code where qemu jumps and I write 0x888 to enable interrupts and set mpp 01 (supervisor) and also set mepc to start_kernel where is the function i why supervisor mode to jump. All the other things are for enabling interrupts and other stuff that I want to believe doesn't really influence at all.

Here is the code if you need me to explain something more in order to help me feel free.

Thanks to all!

_realentry:

la sp, stack

li a2, 1024*4 #definim tamany de pagina a 4096

add sp, sp, a2 #el punter apunta al bottom del stack

li t0, 0x888

csrw mstatus, t0

li a0, 0x0 # desactivem la paginacio per ara

csrw satp, a0

li a0, 0x3fffffffffffff //aixo vol dir totes les direcions de memoria posibles

csrw pmpaddr0, a0 //escribim pq formin part del grup 0

li a0, 0x0f //li donem els permisos f aka NAPOT RWX

csrw pmpcfg0, a0

la t0, start_kernel

csrw mepc, t0 #li diem on vol que salti al mret

li t0, 0x102

csrw sstatus, t0

#definim la delegacio d'interrupcions i excepcions ara pq despres no es poden tocar els registres m

#li t0, 0x00 #1010 0 MTIE = 0 #JJ DISABLE INTERRUPTS

li t0, 0x80 #1010 0 MTIE = 1

csrw mie, t0

li a0, 0xffff

csrw mideleg, a0

li a0, 0xffff

csrw medeleg, a0

li t0, 0x222

csrw sie,t0

la t1, interrupt_handler

csrw stvec, t1

la t0, timer_handler

csrw mtvec, t0

li t0, 1000000

li t1, 0x2004000 #mtimecmp address

sd t0, 0(t1)

mret

.end

[Tommy Murphy]

Isn't this basically a repeat of this thread? 

https://groups.google.com/a/groups.riscv.org/g/sw-dev/c/6woTVCaPFaQ

I gave you some suggestions there but you never responded.

[Xavier Barreto Tomeo]

Yes but not at all.

Now this issue comes about how to jump to supervisor mode.

Sorry for not replying too many things on my head rn

El ds, 15 juny 2024 a les 2:14 Tommy Murphy <tommy_...@hotmail.com> va escriure:

[Tommy Murphy]

> Now this issue comes about how to jump to supervisor mode.

Any use? 

* https://danielmangum.com/posts/risc-v-bytes-timer-interrupts/#jumping-to-supervisor-mode