According to https://gcc.gnu.org/legacy-ml/gcc-patches/2008-03/msg01698.html, the TLS support, including the __tls_lookup function, was added to VxWorks in 6.6.
It certainly doesn't exist on our VxWorks 5 platform, but the fallback code in eh_globals.cc using __gthread_key_create() etc. used to work just fine. libstdc++-v3/ChangeLog: * config/os/vxworks/os_defines.h (_GLIBCXX_HAVE_TLS): Only define for VxWorks >= 6.6. --- libstdc++-v3/config/os/vxworks/os_defines.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/libstdc++-v3/config/os/vxworks/os_defines.h b/libstdc++-v3/config/os/vxworks/os_defines.h index c881b2b4b9e..75a68bc605b 100644 --- a/libstdc++-v3/config/os/vxworks/os_defines.h +++ b/libstdc++-v3/config/os/vxworks/os_defines.h @@ -45,8 +45,10 @@ #define _GLIBCXX_USE_WEAK_REF 0 #endif -// We support TLS on VxWorks (either directly or with emutls) +// We support TLS on VxWorks >= 6.6 (either directly or with emutls) +#if !_VXWORKS_PRE(6, 6) #define _GLIBCXX_HAVE_TLS 1 +#endif // VxWorks7 comes with a DinkumWare library and the system headers which we // are going to include for libstdc++ have a few related intrinsic -- 2.31.1