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authorGravatar Thomas Petazzoni <thomas.petazzoni@free-electrons.com>2014-05-13 23:47:37 +0200
committerGravatar Peter Korsgaard <peter@korsgaard.com>2014-05-14 09:24:53 +0200
commit5035b7819ccda95f2b1bbc5fb99175f5dbe26b37 (patch)
tree1d2c1640d6bfc34b3498dd4fda485466360a84ee /package/libunwind
parent63bf62a4738545466b8e6d3b2b21bd338dae8281 (diff)
downloadbuildroot-5035b7819ccda95f2b1bbc5fb99175f5dbe26b37.tar.gz
buildroot-5035b7819ccda95f2b1bbc5fb99175f5dbe26b37.tar.bz2
libunwind: add patch to fix behavior for ARM < v6
Since libatomic_ops does not implement real atomic operations for ARMv4 and ARMv5, libunwind must define AO_REQUIRE_CAS do indicate it requires compare-and-swap operations, even if not available as real atomic operations for the current architecture. In this case, libatomic_ops will rely on emulated atomic operations, which also require linking against libatomic_ops, which was until now not done by libunwind. This fixes the mysterious ltrace build issue: http://autobuild.buildroot.org/results/e1b/e1b330abfa2d80f3f30bc3359428ea429c690eb8/ Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com> Cc: Baruch Siach <baruch@tkos.co.il> Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Diffstat (limited to 'package/libunwind')
-rw-r--r--package/libunwind/libunwind-01-disable-tests.patch (renamed from package/libunwind/libunwind-disable-tests.patch)0
-rw-r--r--package/libunwind/libunwind-02-Add-AO_REQUIRE_CAS-to-fix-build-on-ARM-v6.patch56
-rw-r--r--package/libunwind/libunwind.mk1
3 files changed, 57 insertions, 0 deletions
diff --git a/package/libunwind/libunwind-disable-tests.patch b/package/libunwind/libunwind-01-disable-tests.patch
index 05475a5d6c..05475a5d6c 100644
--- a/package/libunwind/libunwind-disable-tests.patch
+++ b/package/libunwind/libunwind-01-disable-tests.patch
diff --git a/package/libunwind/libunwind-02-Add-AO_REQUIRE_CAS-to-fix-build-on-ARM-v6.patch b/package/libunwind/libunwind-02-Add-AO_REQUIRE_CAS-to-fix-build-on-ARM-v6.patch
new file mode 100644
index 0000000000..2a37ed7784
--- /dev/null
+++ b/package/libunwind/libunwind-02-Add-AO_REQUIRE_CAS-to-fix-build-on-ARM-v6.patch
@@ -0,0 +1,56 @@
+From 24484e80b3e329c9edee1995e102f8612eedb79c Mon Sep 17 00:00:00 2001
+From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+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
+<atomic_ops.h> 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 <thomas.petazzoni@free-electrons.com>
+---
+ 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 <atomic_ops.h>
+ static inline int
+ cmpxchg_ptr (void *addr, void *old, void *new)
+--
+1.9.2
+
diff --git a/package/libunwind/libunwind.mk b/package/libunwind/libunwind.mk
index f573722f90..48dd0ec5bb 100644
--- a/package/libunwind/libunwind.mk
+++ b/package/libunwind/libunwind.mk
@@ -9,5 +9,6 @@ LIBUNWIND_SITE = http://download.savannah.gnu.org/releases/libunwind
LIBUNWIND_INSTALL_STAGING = YES
LIBUNWIND_LICENSE_FILES = COPYING
LIBUNWIND_LICENSE = MIT
+LIBUNWIND_AUTORECONF = YES
$(eval $(autotools-package))