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Altera_Forum's avatar
Altera_Forum
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12 years ago

Nios doesn't boot using custom bootloader

Hi, I have implemented the remote_update function on my custom board and it works for HW images. Now I am trying to boot nios images from non standard offset but it does not work :-/. I ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
12 years ago

Be sure that you understand that the EPCS bootloader does not reside in the EPCS flash, itself, but rather in a small onchip (i.e. _on_ FPGA) memory that is a part of the epcs_controller. Any changes you make to the EPCS bootloader must be built into that onchip memory and re-compiled in Quartus II.

If you already understand that portion (it looks like you do), then you're already making sure that this happens and that the instructions you see in that onchip memory match what you'd expect to see in your customer bootloader.

Also, any reason that you're using 11.1sp2? It's a pretty old version is all. You could also replace it with non-assembly code as well. If I recall, there's a single command in the EPCS API that will pretty much do this for you...not sure if it will fit into the 1k bytes that are part of the epcs_controller though. You'd likely have to use another onchip memory....It would be easier to debug/test though.

...I have definitely done this before, so I know it's possible.