Hello,
[Adding Rich in Cc.]
On Fri, 19 Aug 2016 19:34:43 +0200, Waldemar Brodkorb wrote:
Do we have a
list of the pthread functions that libc.so/libc.a is
supposed to provide? See the mail I just send about the axel/libintl
issue where libintl also uses pthread_rwlock_*() without being linked
with libpthread.so.
I discussed the issues with Rich Felker and he is suggesting _not_
to do some wacky weak/strong handling of these symbols to provide
some hackish way for applications to save some space.
We should just link with -lpthread if any pthread_* function is in
use to avoid any surprises when actually running the application.
So please add explicit -lpthread for these static linking failures
and add in libpthread.a functions. It might be just by accident that
libc.so provides these function dummies for external uses and may be
we should fix this instead.
I'm sorry but I disagree with Rich's proposal here. Lots of libraries
rely on this behavior, and we will not be able to upstream the change
that consists in linking with -lpthread, because it means a performance
degradation when those libraries are used in mono-threaded applications.
It is *not* about saving some space like Rich said. It is about making
the mutex lock/unlock operations no-ops when they are not needed.
So I'm sorry, but uClibc should implement this behavior, or you will
have dozens of upstream projects to convince :-/
Thomas
--
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com