Comment by uecker
1 month ago
It should not be necessary to freeze it. glibc is already extremely backwards compatible. The problem is people distributing programs that request the newest version even though they do not really require it, and this then fails on systems having an older version. At least this is my understanding.
The actual practical problem is not glibc but the constant GUI / desktop API changes.
Making an executable “request” older symbol versions is incredibly painful in practice. Basically every substantial piece of binary software either compiles against an ancient Debian sysroot (that has to have workarounds for the ancient part) or somehow uses a separate glibc copy from the base system (Flatpak, etc.). The first greatly complicates building the software, the second is recreating Windows’ infamous DLL hell.
Both are way more annoying than anything the platforms without symbol versioning suffer from because of its lack. I’ve never encountered anyone who has packaged binaries for both Linux and Windows (or macOS, or the BSDs) that missed anything about Linux userspace ABIs when working with another platform.
Is it painful? Why? You need a build environment that has the old libraries. It does not have to be ancient, just exactly what you need.
It has to be as ancient as the oldest glibc you want to support, usually a Red Hat release with very old version and manual security backports. These can have nearly decade-old glibc versions, especially if you care about extended support contracts.
You generally have difficulty actually running contemporary build tools on such a thing, so the workaround is to use —-sysroot against what is basically a chroot of the old distro, as if cross-compiling. But there are still workarounds needed if the version is old enough. Chrome has a shorter support window than some Linux binaries, but you can see the gymnastics they do to create their sysroot in some Python scripts in the chromium repo.
On Windows, you install the latest SDK and pass a target version flag when setting up the compiler environment. That’s it. macOS is similar.
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