On Fri, Jan 14, 2022 at 7:32 AM Jakub Jelinek <jakub(a)redhat.com> 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).
I don't know if this change is involved, but I've got several packages
that failed to build on ppc64le only, with what look like gcc
segfaults:
- cli11:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81476792
- dra2ter:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81482527
- libfplll:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81533813
- libpoly:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81536797
- mp:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81548297
- python-fpylll:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81597035
Also note that libmpc failed to build on ppc64le only:
https://koji.fedoraproject.org/koji/taskinfo?taskID=81535783
Since gcc uses libmpc, it's probably important to look at that one carefully.
--
Jerry James
http://www.jamezone.org/