On Tue, 7 Nov 2017, Josh Poimboeuf wrote:
> > Is there some technical reason why do you want to avoid > > CONFIG_GUESS_UNWINDER? > > The technical reason for avoiding the guess unwinder is that it's > sketchy: it gives false positive results. I've always used kernels without frame pointer and I don't see any problem with decoding stack traces with some phantom entries that were left in the stack - it's easy to find out which functions could call which functions and discard the phantom entries. > Not only for oopses, but for all the other users of the unwinder: > /proc/<pid>/stack, perf, lockdep, etc. So it's a correctness issue. Experts need these features, but casual users don't. > I agree with you that the frame pointer unwinder has drawbacks, but if > somebody cares about those drawbacks, I would consider that person an > "expert" ;-) The Kconfig entry says that frame pointers degrade performance by 5-10% - so almost any user would care about it, not just experts. Mikulas
