Date: Sat, 31 Mar 2007 04:26:23 +0200 From: Pieter de Goeje <pieter@degoeje.nl> To: freebsd-hackers@freebsd.org Subject: Thread local storage not working with -fPIC and shared objects Message-ID: <200703310426.23953.pieter@degoeje.nl>
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Hello List,
I have these files:
--- loader.cpp ---
#include <stdio.h>
#include "tls.h"
int main() {
tls = 0;
printf("%d\n", tls);
}
--- tls.cpp ---
#include "tls.h"
int __thread tls;
--- tls.h ---
extern __thread int tls;
When I compile them like this:
c++ -fPIC -o tls.so tls.cpp -shared
c++ -fPIC -o loader loader.cpp tls.so
And run the resulting program, I get:
pyotr@nox:~/projects/misc/tls> ./loader
/libexec/ld-elf.so.1: ./loader: Unsupported relocation type 37 in non-PLT
relocations
When I omit -fPIC, it runs fine. But I need fPIC for the shared object on
amd64 arch. I've tried it on Linux/i386 (gcc 4.1) and it ran fine (with
fPIC).
Much to my surprise however, a particularly large application I'm working on
did compile & run on FreeBSD/amd64 using -fpic (lowercase) and gcc 4.3.
Trying -fpic on FreeBSD/i386 resulted in failure.
FYI, I need tls to work because I'm using OpenMP's tls (#pragma omp
threadprivate()) support in gcc 4.3.
The workaround I found on FreeBSD/amd64 was linking the main executable
with -fno-PIC, or building everything with -fpic. (both workarounds didn't
work on FreeBSD/i386)
I would be grateful if someone could shed some light on this.
Regards,
Pieter de Goeje
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