On Mon, 14 Jul 2014, Kurt Roeckx wrote: > I plan to try and get them to use symbol versioning, at least on > those platforms that support it. This will probably be just like
Thank you. > the patch currently in Debian. I don't plan to add multiple > versions of a symbol to try and keep the same soname since that > probably won't work on all platforms. We want _all_ visible libressl symbols versioned, but that's for protective namespacing, and not for backwards binary compatibility. That's why it should be a libressl-specific symbol version, since full guaranteed *internal* ABI compatibility with openssl is not really happening. We've been through this hell with libpng, libsasl, and openssl itself... I still think we should forbid any libraries with unversioned symbols in Debian, unless they're guaranteed to never be linked by other libraries (including nss modules and the like). Solaris got this idea right nearly two decades ago. Use of symbol versioning for providing several versions of the same symbol for backwards binary compatibility (like it is done by glibc) has its own problems and limitations. Those were rehearsed ad nauseam some years ago, and that's _not_ what we're talking about here, anyway. > We also plan to reduce the risk of breaking the ABI. Now a lot of > structs are public and we would like to make them private and > provide functions for those things that people want to access. Seems sensible. > This will all probably take some time. As long as you don't mean to wait to deploy symbol versioning. It becomes *really* painful after a while. Changes to symbol versioning requires everyone to recompile everything that uses the library. It is bad enough when you go from unversioned to versioned symbols (the binary will still run but you get a warning about it every time), but it is hell when you switch[1] symbol versioning decoupled from a major soname bump, because everything that is not recompiled with the new symbols will fail to runtime link, requiring coordinated transitions/flag-days to avoid this. [1] as in change the namespace, and _not_ as in provide a new version of symbols while also providing the older versions of the symbol around. -- "One disk to rule them all, One disk to find them. One disk to bring them all and in the darkness grind them. In the Land of Redmond where the shadows lie." -- The Silicon Valley Tarot Henrique Holschuh -- To UNSUBSCRIBE, email to debian-bugs-dist-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org
