glibc: Allow 64 bit atomics for x86

The fix consist of allowing 64bit atomic ops for x86.
This should be safe for i586 and newer CPUs.
It also makes the synchronization more efficient.

[YOCTO #8140]

Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

diff --git a/meta/recipes-core/glibc/glibc/use_64bit_atomics.patch b/meta/recipes-core/glibc/glibc/use_64bit_atomics.patch
new file mode 100644 (file)
index 0000000..eb7f2b2
--- /dev/null
+++ b/meta/recipes-core/glibc/glibc/use_64bit_atomics.patch
@@ -0,0 +1,24 @@
+This patch alows using 64 bit atomic instructions on a
+32 bit platform. This is safe, providing x86 is Pentium or
+later (would not work on i386, i486). Using 64 bit atomic 
+instructions bypasses code containing a bug as documented in
+https://bugzilla.yoctoproject.org/show_bug.cgi?id=8140
+
+Upstream-Status: TBD
+
+Signed-off-by: Juro Bystricky <juro.bystricky@intel.com>
+
+
+Index: libc/sysdeps/i386/i486/bits/atomic.h
+===================================================================
+--- libc.orig/sysdeps/i386/i486/bits/atomic.h
++++ libc/sysdeps/i386/i486/bits/atomic.h
+@@ -54,7 +54,7 @@ typedef uintmax_t uatomic_max_t;
+ # endif
+ #endif
+ 
+-#define __HAVE_64B_ATOMICS 0
++#define __HAVE_64B_ATOMICS 1
+ #define USE_ATOMIC_COMPILER_BUILTINS 0
+ 
+ 

diff --git a/meta/recipes-core/glibc/glibc_2.22.bb b/meta/recipes-core/glibc/glibc_2.22.bb
index 020e417dd5b0ad50817ada9605c6abd71c506542..2494ad7d971b66fdcc5c34721e14f16fc78b4224 100644 (file)
--- a/meta/recipes-core/glibc/glibc_2.22.bb
+++ b/meta/recipes-core/glibc/glibc_2.22.bb
@@ -50,6 +50,7 @@ SRC_URI_append_class-nativesdk = "\
            file://0001-nativesdk-glibc-Look-for-host-system-ld.so.cache-as-.patch \
            file://0002-nativesdk-glibc-Fix-buffer-overrun-with-a-relocated-.patch \
            file://0003-nativesdk-glibc-Raise-the-size-of-arrays-containing-.patch \
+           file://use_64bit_atomics.patch \
 "
 
 S = "${WORKDIR}/git"