Re: Fwd: MIPSEL GLIBC sem_init() not shared

[Florian Weimer <fweimer@redhat.com>]

* Alessandro Carminati via Libc-help:

> This time was the port on MIPSEL, but before this port, I compiled
> successfully (without -lpthread) on two other architectures: ARM32 and
> x64.  Which is the mechanism why in other architecture, the libpthread
> was included and in MIPS it didn't?

32-bit Arm starts at GLIBC_2.4, x86-64 starts at GLIBC_2.2.5.  The old
versions aren't there, so an underlinked library cannot bind against
them.

> My question is, why it resolved the call picking the
> sem_init@GLIBC_2.0 instead of sem_init@@GLIBC_2.2?

glibc originally did not have symbol versioning, so for backwards
compatibility, unversioned binaries need to pick the oldest available
version.  In theory, we could provide better diagnostics.  But we're
working on moving all libpthread symbols in to libc.so.6, so that their
versions are always visible to the link editor (unless you link with
-nostdblib, but then you are on your own anyway).  That's why the
diagnostics do not seem to be particularly useful in the medium term.

Thanks,
Florian