I will consider this possibilities, thanks. What is driving me crazy is that it actually seems to be triggered by the binary being bigger than 256KB (MCU has 512KB, dual bank). I already had to use openocd from git since it would not flash the image in that case. Now openocd flashes correctly. However, the bad reset behavior also seems to happen in this case. I have the same problem with optimization turned on but which increases binary size above 256KB. I cannot think something in the code that would change in this case, since banks are contiguous. Maybe some chip errata, I don't know.
Yes, I do recall some issue with the F429's in this regard. There was an errata. I believe that there are some pins in the upper 256Kb bank that interfered with some other peripheral. DavidS would know better than I. I thought it effected USB?
You never mention which part you are using (or perhaps wan't paying attention). You should check the errata.
