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authorHirokazu Takata <takata.hirokazu@renesas.com>2007-05-10 22:22:25 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-05-11 08:29:33 -0700
commit43c09ce7927912c7867617cba0a265beea38a154 (patch)
tree0b0a8b8e9a5f9b2e1fe7aa058378f23321f2a910 /arch
parenth8300 syscall update (diff)
downloadlinux-dev-43c09ce7927912c7867617cba0a265beea38a154.tar.xz
linux-dev-43c09ce7927912c7867617cba0a265beea38a154.zip
m32r: fix switch_to macro to push/pop frame pointer if needed
This patch fixes a rarely-happened but severe scheduling problem of the recent m32r kernel of 2.6.17-rc3 or later. In the following previous m32r patch, the switch_to macro was modified not to do unnecessary push/pop operations for tuning. > [PATCH] m32r: update switch_to macro for tuning > 4127272c38619c56f0c1aa01d01c7bd757db70a1 In this modification, only 'lr' and 'sp' registers are push/pop'ed, assuming that the m32r kernel is always compiled with -fomit-frame-pointer option. However, in 2.6 kernel, kernel/sched.c is irregularly compiled with -fno-omit-frame-pointer if CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER is not defined. -- kernel/Makefile -- : ifneq ($(CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER),y) # According to Alan Modra <alan@linuxcare.com.au>, the -fno-omit-frame-pointer is # needed for x86 only. Why this used to be enabled for all architectures is beyond # me. I suspect most platforms don't need this, but until we know that for sure # I turn this off for IA-64 only. Andreas Schwab says it's also needed on m68k # to get a correct value for the wait-channel (WCHAN in ps). --davidm CFLAGS_sched.o := $(PROFILING) -fno-omit-frame-pointer endif : --- Therefore, for the recent m32r kernel, we have to push/pop 'fp' (frame pointer) if CONFIG_FRAME_POINTER is defined or CONFIG_SCHED_NO_NO_OMIT_FRAME_POINTER is not defined. Signed-off-by: Hitoshi Yamamoto <hitoshiy@linux-m32r.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/m32r/Kconfig4
1 files changed, 4 insertions, 0 deletions
diff --git a/arch/m32r/Kconfig b/arch/m32r/Kconfig
index 9740d6b8ae11..c3bb8a755b00 100644
--- a/arch/m32r/Kconfig
+++ b/arch/m32r/Kconfig
@@ -241,6 +241,10 @@ config GENERIC_CALIBRATE_DELAY
bool
default y
+config SCHED_NO_NO_OMIT_FRAME_POINTER
+ bool
+ default y
+
config PREEMPT
bool "Preemptible Kernel"
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