On Mon, Jan 30, 2023 at 02:09:18PM +0100, Petr Pisar wrote: > V Sat, Jan 28, 2023 at 06:12:11PM -0800, Gordon Messmer napsal(a): > > > > I don't think convincing hundreds or thousands of developers to add symbol > > versioning to their libraries is a viable solution. I'd love to see it > > happen, but rpm/dnf should be more reliable in the meantime. > > > Is symbol versioning portable across toolchains? I.e. is the linker script > with symbol aliases understandible by other tools than (llvm|gcc)+binutils? > I speak about upstreams who do not want to impede building e.g. on FreeBSD, > Windows, or Solaris.
It only applies to ELF platforms. It also works fine with Clang. FreeBSD uses ELF but their linker has issues with wildcards in the linker script so we had to disable it there: https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=190851 macOS doesn't use ELF and doesn't support linker scripts, so obviously disabled there too. Windows (PE) linking has entirely its own set of complexities and strangeness, but I don't think there's anything quite like symbol versioning. Symbol versioning makes it tricky to backport an upstream patch to downstream (eg. to RHEL) if the patch adds a new API. You have to decide whether or not to add a new version to the linker script or put the symbol into one of the old sections, and I seem to recollect there is no always good answer. Nevertheless I think symbol versioning is a worthwhile thing to do. Some examples of projects using linker scripts and/or symbol versioning: https://gitlab.com/nbdkit/nbdkit - linker script only, to hide symbols https://gitlab.com/nbdkit/libnbd - linker script + versioning, everything is generated from a machine-readable description of the API https://gitlab.com/libvirt/libvirt - extensive use of linker scripts + symbol versioning, see the src/*.syms files Rich. -- Richard Jones, Virtualization Group, Red Hat http://people.redhat.com/~rjones Read my programming and virtualization blog: http://rwmj.wordpress.com virt-p2v converts physical machines to virtual machines. Boot with a live CD or over the network (PXE) and turn machines into KVM guests. http://libguestfs.org/virt-v2v _______________________________________________ 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, report it: https://pagure.io/fedora-infrastructure/new_issue
