The ABI status of ELF hash tables

Posted Aug 20, 2022 9:28 UTC (Sat) by drago01 (subscriber, #50715)
Parent article: The ABI status of ELF hash tables

This change is an ABI break by every definition of an ABI break. Claiming otherwise is just silly.

The ABI status of ELF hash tables

Posted Aug 20, 2022 23:41 UTC (Sat) by josh (subscriber, #17465) [Link] (1 responses)

I'm normally all for "any interface people rely on is ABI", as the Linux kernel does. But there's a limit to that. Suppose something hashed the assembly code of `memcpy` and broke if it changed? Suppose something hashed ld-linux.so (the dynamic linker) and broke if it changed? Would you consider those "ABI"?

The ABI status of ELF hash tables

Posted Aug 21, 2022 5:44 UTC (Sun) by drago01 (subscriber, #50715) [Link]

No, but in that case it is even documented.

The ABI status of ELF hash tables

Posted Aug 22, 2022 14:40 UTC (Mon) by larkey (guest, #104463) [Link] (2 responses)

Yep, I often find myself on the GNU side of things (despite still being heart broken over Solaris) but this?! DT_HASH is

* standard
* universally available
* never officially deprecated (blog posts don't count)
* documented
* cross platform

The GNU alternative is

* GNU/Linux specific
* undocumented
* non-standard

Simply removing it is just absurd and the reason stated is also just sad. If I care about a *very* small foot print I wouldn't be using the GNU tooling anyway, likely :-)

I also find it appalling that they say that they are somehow "upstream ELF development" and further that everyone dealing with this need to follow all their blogs? This is just hybris.

The ABI status of ELF hash tables

Posted Aug 23, 2022 15:12 UTC (Tue) by JanC_ (guest, #34940) [Link]

DT_HASH wasn’t removed though, it’s just no longer included by default if you use the upstream build options.

The GNU/glibc people should have documented this better though (both the new table format as well as the changes to the defaults). Based on that, operating systems (distros) could then choose to maintain compatibility with SysV or not.

The ABI status of ELF hash tables

Posted Sep 6, 2022 8:52 UTC (Tue) by nix (subscriber, #2304) [Link]

> I also find it appalling that they say that they are somehow "upstream ELF development"

Looking at it practically... they are, and have been for well over a decade at this point. Perhaps 15--17 years: i.e., since about as long ago as the introduction of DT_GNU_HASH!