On Wed, Oct 16, 2019 at 09:42:17AM +0200, Peter Zijlstra wrote: > > which are not compatible with livepatching. GCC upstream now has > > -flive-patching option, which disables all those interfering optimizations. > > Which, IIRC, has a significant performance impact and should thus really > not be used... > > If distros ship that crap, I'm going to laugh at them the next time they > want a single digit performance improvement because *important*. I have a crazy plan to try to use objtool to detect function changes at a binary level, which would hopefully allow us to drop this flag. But regardless, I wonder if we enabled this flag prematurely. We still don't have a reasonable way to use it for creating source-based live patches upstream, and it should really be optional for CONFIG_LIVEPATCH, since kpatch-build doesn't need it. -- Josh
