On Fri, Mar 01, 2019 at 10:24:18AM -0600, Josh Poimboeuf wrote: > > Is there a reason why the top-level Makefile only sets > > -fno-optimize-sibling-calls if CONFIG_FRAME_POINTER is set? > > I suspect that this is just a historical thing, because reliable > > unwinding didn't work without frame pointers until ORC came along. > > I'm not quite sure how best to express "don't do tail optimization if > > either frame pointers are used or ORC is used" in a Makefile, and > > whether we want an indirection through Kconfig for that, so I'm not > > doing anything about it in this series. > > Can someone send a patch to deal with it properly? > > Why would sibling calls be a problem for ORC? Once a function does a > sibling call, it has effectively returned and shouldn't show up on the > stack trace anyway. Answering my own question, I guess some people might find it confusing to have a caller skipped in the stack trace. But nobody has ever complained about it. It's not a problem for livepatch since we only care about the return path. -- Josh
