Hi there,
I am trying to run baremetal programs on the Milk V Duo using Fiptool. I was successful in having some blinking LEDs and LCD display, however, I wanted to play with interrupts. That lead me to the PLIC (which is on address 0x70000000) but when I try to read the enable bit for the particular timer interrupt (in M-mode!!!), the CPU gives me an exception with exception 5, which means “Load instruction access error exception”.
Does anyone know how to solve this issue?
Is that timer interrupt allowed to be accessed by that core? Just wondering, I’m far from experimenting bare metal yet.
I think I solved it. I was running my program on top of OpenSBI which had set-up the environment “for me”. When I tried to access the PLIC, it was an illegal memory access. When I removed OpenSBI and just let my program be directly booted by the 2nd stage bootloader, it works fine!
Really curious about baremetal. I know there’s another thread on this forum that gives some tantalizing detail, but so far no one has published any code - just some rough handwaving in the general direction of the first-stage bootloader. Would love to see someone post a github repo with code.
The only repo I found that talks about bare metal development on the Milk V Duo is this one: GitHub - unicornx/bm4duo . Unfortunately, the majority of it is in Chinese (which is not surprising but I don’t speak any). There are a lot of great examples.
I am working on my bachelor thesis and I will be probably using the Milk V Duo (and the CV1800B processors). I will document everything and in some time, I’ll post it in a public GitHub repository.
Looking forward to seeing what you manage to find out and achieve. I’m sincerely interested in developing something funny and/or useful on Duo boards.
Good luck wth your thesis and thanks for the pointers.
That is great. Anxious to see your development.