On Sun, 16 Jan 2022 19:27:44 +0100 Jakub Jelinek <ja...@redhat.com> wrote:
> On Fri, Jan 14, 2022 at 04:07:08PM +0100, Dan Horák wrote: > > > Another important thing I wanted to say is that we'd like to switch > > > ppc64le from the numerically problematic IBM extended long double to > > > IEEE 754 quad long double. This is an ABI change. Some libraries > > > are already built so that they support both ABIs at the same time, > > > including glibc, libstdc++, libgcc, libgfortran etc. > > > For other libraries and binaries, the compiler, assembler and linker > > > will notice if they use long double and flag them as using either > > > IBM or IEEE long double and linker (or I think dynamic linker too) > > > might complain when things are mixed. > > > Right now the rawhide gcc still defaults to -mabi=ibmlongdouble > > > but the glibc/gcc libraries are built compatibly with both. > > > We'd like to configure gcc shortly before the mass rebuild with > > > --with-long-double-format=ieee so that it will default to > > > -mabi=ieeelongdouble, probably on a side-tag build first, and it > > > will be highly desirable to rebuild at least some of the most commonly > > > used library packages in the order of dependencies there, otherwise > > > I'd be afraid the mass rebuild could fail for way too many packages > > > (as the mass rebuild doesn't do dependency order rebuilds but just > > > goes through packages alphabetically or so). > > > Any suggestions on which packages have commonly used library packages > > > that use long double? > > > readelf -A on libraries on ppc64le prints either nothing (either > > > the library is thought not to use long double or supports both ABIs > > > transparently or hasn't been rebuilt for some years), or > > > Attribute Section: gnu > > > File Attributes > > > Tag_GNU_Power_ABI_FP: hard float, 128-bit IBM long double > > > for libraries (or binaries or object files) that use IBM long double > > > only or > > > Attribute Section: gnu > > > File Attributes > > > Tag_GNU_Power_ABI_FP: hard float, 128-bit IEEE long double > > > for IEEE long doubles. > > > So I think we want to rebuild on a side-tag packages that > > > provide shared libraries used by hundreds of other packages that > > > are > > > Tag_GNU_Power_ABI_FP: hard float, 128-bit IBM long double > > > right now. > > > > a quick&dirty scan of /usr/lib64 on my F-34 workstation shows > > many ./libQt5* > > many ./libLLVM* > > ./libgobject-2.0 > > ./libgio-2.0 > > ./libglib-2.0 > > ./libexiv2-xmp > > ./libhwy > > ./python3.9/site-packages/numpy/* > > ./libSDL2 > > ./libiberty > > ./clang/12.0.1/lib/libclang_rt.builtins-powerpc64le.a > > ./ghdl/llvm/libgrt.a > > ./libc > > > > as users of the Tag_GNU_Power_ABI_FP attribute. A vast majority of the > > hits are "Tag_GNU_Power_ABI_FP: hard float, unspecified long double" > > > > Translated to packages it is qt5-*, llvm + clang, numpy, SDL2, glib2, > > exiv2, glibc, highway > > The -mabi=ieeelongdouble defaulting gcc is now in the > f36-build-side-49600 side-tag (gcc -0.5.1.fc36, same as -0.5.fc36 in > rawhide except for the different ppc64le default ABI). is it right, that the attribute appears only in static libs? I did a scratch build for glib2 (https://koji.fedoraproject.org/koji/taskinfo?taskID=81396901) and "readelf -A libglib-2.0.so.0.7100.0" shows nothing, but "readelf -A libglib-2.0.a" returns "Tag_GNU_Power_ABI_FP: hard float, 128-bit IEEE long double" for some *.o files in the archive. Dan _______________________________________________ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
