1 files changed, 48 insertions, 0 deletions

diff --git a/meta/recipes-kernel/linux/files/1300-fix-gcc-4.3-false-modulo-optimization.patch.patch b/meta/recipes-kernel/linux/files/1300-fix-gcc-4.3-false-modulo-optimization.patch.patch
new file mode 100644
index 0000000000..3ff0c07c18
--- /dev/null
+++ b/meta/recipes-kernel/linux/files/1300-fix-gcc-4.3-false-modulo-optimization.patch.patch
@@ -0,0 +1,48 @@
+From f5b973489beb1a1239dfad53e3ad6e36ff7ee958 Mon Sep 17 00:00:00 2001
+From: Segher Boessenkool <segher@kernel.crashing.org>
+Date: Thu, 9 Oct 2008 21:18:27 +0100
+Subject: [PATCH] fix-gcc-4.3-false-modulo-optimization.patch
+
+I tried to compile the current stable kernel
+(a2ef813d2f439a3e9f377d33a2e5baad098afb7e)
+and get the following errors:
+
+kernel/built-in.o: In function `timespec_add_ns':
+/mnt/data/Freerunner/Gentoo/rootinstall/usr/src/linux/include/linux/time.h:174:
+undefined reference to `__aeabi_uldivmod'
+/mnt/data/Freerunner/Gentoo/rootinstall/usr/src/linux/include/linux/time.h:179:
+undefined reference to `__aeabi_uldivmod'
+/mnt/data/Freerunner/Gentoo/rootinstall/usr/src/linux/include/linux/time.h:174:
+undefined reference to `__aeabi_uldivmod'
+/mnt/data/Freerunner/Gentoo/rootinstall/usr/src/linux/include/linux/time.h:179:
+undefined reference to `__aeabi_uldivmod'
+
+applying the following patch solved the problem:
+--------
+Prevent gcc-4.3 form "optimizing" the while loop into a costly modulo operation.
+Patch found at http://lkml.org/lkml/2008/2/22/464.
+
+Reported-by: Sven Rebhan <odinshorse@googlemail.com>
+Signed-off-by: Segher Boessenkool <segher@kernel.crashing.org>
+---
+ include/linux/time.h |    4 ++++
+ 1 files changed, 4 insertions(+), 0 deletions(-)
+
+diff --git a/include/linux/time.h b/include/linux/time.h
+index b04136d..3e8fd9e 100644
+--- a/include/linux/time.h
++++ b/include/linux/time.h
+@@ -173,6 +173,10 @@ static inline void timespec_add_ns(struct timespec *a, u64 ns)
+ {
+        ns += a->tv_nsec;
+        while(unlikely(ns >= NSEC_PER_SEC)) {
++               /* The following asm() prevents the compiler from
++                * optimising this loop into a modulo operation.  */
++               asm("" : "+r"(ns));
++
+                ns -= NSEC_PER_SEC;
+                a->tv_sec++;
+        }
+-- 
+1.5.6.5
+