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Any idea about instructions marked as UNPREDICTABLE: can it then be UNDEFINED?
In other words: UNDEFINED REQUIRES the instruction to cause UND-exception, but
MAY UNPREDICTABLE do that, or does it have to execute normally except that the result may be whatever?
(I'm not yelling even if I used caps.)
I did as that same thing there Re: ARM/THUMB instructions that change execution path?
but I don't seem to get any answers. And this is probably more appropriate space anyway.
Aha :)
BKPT only exists ARMv5 and above so debuggers that attempt to support older architectures instead use a known unallocated encoding to trap instructions as Undef. If you're only concerned about newer cores then maybe you can get away with it - that said if you're arguing that you can handle an abort exception then handling Undef shouldn't be too big a pain.
There's a vector and banked regs set up already. The idea is to catch most exceptions.
I'm writing it specifically to my Raspberry Pi 2B (but I hope it'll work on the other RPi-versions too).
This is my private "blinky"-project, except that it doesn't blink a LED.
(Isn't that usually the first ever program on new HW?)
The SW I'm trying to put together is some kind of standalone gdb-stub (with included serial I/O).
It should be able to load a program via the serial line and debug it.
At the moment only single core is supported.