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That's interesting, how does glibc maintain ABI compatibility? Alias attributes? Even if glibc does it, if other libraries expose time_t in their ABI and don't

That's interesting, how does glibc maintain ABI compatibility? Alias attributes? Even if glibc does it, if other libraries expose time_t in their ABI and don't do the same, then it's the same problem.

mananaysiempre 5y ago
> [H]ow does glibc maintain ABI compatibility? Alias attributes? Symbol versioning[1,2]. Kind of like aliases, but more awkward. In theory it’s not specific to glibc, in practice hardly anyone else bothers being so careful about their ABI. Note that dynamically linked musl, which Alpine uses (I think..?), doesn’t understand symbol versioning, though I expect this will only last until the first ABI break in musl. [1]: https://www.akkadia.org/drepper/symbol-versioning https://www.akkadia.org/drepper/symbol-versioning [2]: https://maskray.me/blog/2020-11-26-all-about-symbol-versioning https://maskray.me/blog/2020-11-26-all-about-symbol-versioni...
- Hello71 5y ago
  musl has lasted almost one-third as long as glibc, with significantly less than one-third the number of ABI breaks. as far as I know, the only musl ABI break has been time64; despite glibc's supposedly superior version handling, musl has completed time64 support with headers only, whereas glibc is still in progress.
- leni536 5y ago
  > Symbol versioning I know that glibc uses symbol versioning to remain ABI-compatible within versions. What I meant was ABI compatibility between 32-bit and 64-bit time_t with the same glibc library. Looks like it uses something like aliases for that (but self-implemented using asm): https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/select.h;h=e9c0e8fc201a75807327c6b0c786c132666b4004;hb=HEAD#l134 https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/se... https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/cdefs.h;h=a05b538579b8801b7a30407fe8770e46d0261234;hb=HEAD#l246 https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/cd...

mananaysiempre 5y ago

> [H]ow does glibc maintain ABI compatibility? Alias attributes? Symbol versioning[1,2]. Kind of like aliases, but more awkward. In theory it’s not specific to glibc, in practice hardly anyone else bothers being so careful about their ABI. Note that dynamically linked musl, which Alpine uses (I think..?), doesn’t understand symbol versioning, though I expect this will only last until the first ABI break in musl. [1]: https://www.akkadia.org/drepper/symbol-versioning https://www.akkadia.org/drepper/symbol-versioning [2]: https://maskray.me/blog/2020-11-26-all-about-symbol-versioning https://maskray.me/blog/2020-11-26-all-about-symbol-versioni...

Hello71 5y ago
musl has lasted almost one-third as long as glibc, with significantly less than one-third the number of ABI breaks. as far as I know, the only musl ABI break has been time64; despite glibc's supposedly superior version handling, musl has completed time64 support with headers only, whereas glibc is still in progress.
leni536 5y ago
> Symbol versioning I know that glibc uses symbol versioning to remain ABI-compatible within versions. What I meant was ABI compatibility between 32-bit and 64-bit time_t with the same glibc library. Looks like it uses something like aliases for that (but self-implemented using asm): https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/select.h;h=e9c0e8fc201a75807327c6b0c786c132666b4004;hb=HEAD#l134 https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/se... https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/cdefs.h;h=a05b538579b8801b7a30407fe8770e46d0261234;hb=HEAD#l246 https://sourceware.org/git/?p=glibc.git;a=blob;f=misc/sys/cd...