On 12/19/2017 12:13 PM, Arnd Bergmann wrote: > >> I suppose BUG() implies "dead end" like semantics - which ARC was lacking >> before ? > Correct. Using __builtin_trap() here avoids the 'control reaches end of non-void > function' warnings, but then makes us run into the stack size problem that > I work around with the barrier_before_unreachable(). > > It would be good if you could give this a quick test to see if you get sensible > output from the __builtin_trap(); It does, added a BUG() arbit, hits an abort() ... ISA Extn??? : atomic ll64 unalign (not used) ??? ??? : mpy[opt 9] div_rem norm barrel-shift swap minmax swape BPU??? ??? : partial match, cache:2048, Predict Table:16384 BUG: failure at ../arch/arc/mm/tlb.c:827/arc_mmu_init()! Tested-by: Vineet Gupta <vgupta at synopsys.com> FWIW newer ARC gcc actually implements the builtin so we get a trap 5 instruction now, vs., abort() calls before. BTW I missed reading the hunk of your changelog where this addresses the long standing mystery with ARC builds and numerous -Wreturn-type warnings. I always wondered why they were not fixed upstream already, being too lazy to investigate myself, and turns out this was due to this BUG() thingy. phew ! -Vineet
