diff options
| author | Hirokazu Takata <takata.hirokazu@renesas.com> | 2007-05-10 22:22:25 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-05-11 08:29:33 -0700 |
| commit | 43c09ce7927912c7867617cba0a265beea38a154 (patch) | |
| tree | 0b0a8b8e9a5f9b2e1fe7aa058378f23321f2a910 /arch/m32r/Kconfig | |
| parent | 44316634460a6b368ad3160da6cba3b4725a1433 (diff) | |
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/m32r/Kconfig')
| -rw-r--r-- | arch/m32r/Kconfig | 4 |
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" help |