Upstream GCC enables the flag on i686, x86-64, s390x, and we patch it in for aarch64. ppc64, ppc64le, armv7hl/armhfp should use it as well. The flag is needed so that performance/debugging tooling works. glibc cancellation support needs it as well under certain circumstances.
Unsure about armv7hl/armhfp, that doesn't use DWARF unwind info, but some EABI stuff, no idea what this option does in that case, maybe nothing, somebody would need to test that.
ppc64, ppc64le, armv7hl/armhfp do not need it due to differences in stack management. Updating summary.
(In reply to Florian Weimer from comment #2) > ppc64, ppc64le, armv7hl/armhfp do not need it due to differences in stack > management. Updating summary. Disabling this for ppc64/ppc64le (in glibc) seems to have caused a regression causing the elfutils testsuite to be unable to unwind in some cases because of missing CFI in the .eh_frame (CFI only being available through .debug_frame in the external debuginfo package) for glibc functions like raise. See e.g. https://koji.fedoraproject.org/koji/taskinfo?taskID=23812571
(In reply to Mark Wielaard from comment #3) > (In reply to Florian Weimer from comment #2) > > ppc64, ppc64le, armv7hl/armhfp do not need it due to differences in stack > > management. Updating summary. > > Disabling this for ppc64/ppc64le (in glibc) seems to have caused a > regression causing the elfutils testsuite to be unable to unwind in some > cases because of missing CFI in the .eh_frame (CFI only being available > through .debug_frame in the external debuginfo package) for glibc functions > like raise. See e.g. > https://koji.fedoraproject.org/koji/taskinfo?taskID=23812571 Note that this might actually be glibc specific, since this happens on recent f27 too.
I filed bug 1548847 against Fedora gcc. The expectation is that redhat-rpm-config follows the GCC defaults in this area.