On Fri, 18 Sep 2015, David Daney wrote: > We have to be very careful changing the ABI here. > > This is used by almost all userspace code to detect integer division by zero. > Many things like the libgcj runtime use this to generate runtime exceptions, > we don't want to break them. No worries here, integer division by 0 and overflow use `BREAK 7' and `BREAK 6' respectively (or corresponding trap instructions) and these cases are already handled correctly, as I implemented many years ago for regular MIPS user code and recently fixed for MIPS16 code (and less recently for microMIPS code as well). Have a look at `do_trap_or_bp' in arch/mips/kernel/traps.c for details. There's no collision with `BREAK 5'; Linux code would of course have to treat 5 as an unrecognised for traps and would therefore handle the case right in `do_bp' like with kprobe breakpoints. I hope this clears your concerns. Maciej
