From 24484e80b3e329c9edee1995e102f8612eedb79c Mon Sep 17 00:00:00 2001 From: Thomas Petazzoni Date: Tue, 13 May 2014 23:32:27 +0200 Subject: [PATCH] Add AO_REQUIRE_CAS to fix build on ARM < v6 ARM earlier than ARMv6, such as ARMv4 and ARMv5 do not provide optimize atomic operations in libatomic_ops. Since libunwind is using such operations, it should define AO_REQUIRE_CAS before including so that libatomic_ops knows it should use emulated atomic operations instead (even though they are obviously a lot more expensive). Also, while real atomic operations are all inline functions and therefore linking against libatomic_ops was not required, the emulated atomic operations actually require linking against libatomic_ops, so the commented AC_CHECK_LIB test in acinclude.m4 is uncommented to make sure we link against libatomic_ops. Signed-off-by: Thomas Petazzoni --- acinclude.m4 | 8 +------- include/libunwind_i.h | 1 + 2 files changed, 2 insertions(+), 7 deletions(-) diff --git a/acinclude.m4 b/acinclude.m4 index 497f7c2..9c15af1 100644 --- a/acinclude.m4 +++ b/acinclude.m4 @@ -22,11 +22,5 @@ fi]) AC_DEFUN([CHECK_ATOMIC_OPS], [dnl Check whether the system has the atomic_ops package installed. AC_CHECK_HEADERS(atomic_ops.h) -# -# Don't link against libatomic_ops for now. We don't want libunwind -# to depend on libatomic_ops.so. Fortunately, none of the platforms -# we care about so far need libatomic_ops.a (everything is done via -# inline macros). -# -# AC_CHECK_LIB(atomic_ops, main) + AC_CHECK_LIB(atomic_ops, main) ]) diff --git a/include/libunwind_i.h b/include/libunwind_i.h index 23f615e..deabdfd 100644 --- a/include/libunwind_i.h +++ b/include/libunwind_i.h @@ -95,6 +95,7 @@ WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. */ (pthread_mutex_unlock != NULL ? pthread_mutex_unlock (l) : 0) #ifdef HAVE_ATOMIC_OPS_H +# define AO_REQUIRE_CAS # include static inline int cmpxchg_ptr (void *addr, void *old, void *new) -- 1.9.2