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authorAndi Kleen <ak@linux.intel.com>2012-03-28 11:51:18 -0700
committerH. Peter Anvin <hpa@zytor.com>2012-03-30 10:15:21 -0700
commit1873e870fd63ee4b87dbe0125ca373e420fb4987 (patch)
tree2c4d4244c653e374a1d0040e581be60f614f23a7
parent35372a7d45291140a97518a8d1c8cb0e31ee2bb7 (diff)
downloadlinux-1873e870fd63ee4b87dbe0125ca373e420fb4987.tar.bz2
debug: Add CONFIG_READABLE_ASM
Add a config option to disable various gcc compiler optimizations that make assembler listings much harder to read. This is everything that reorders code significantly or creates partial functions. This is mainly to keep kernel hackers sane. Signed-off-by: Andi Kleen <ak@linux.intel.com> Link: http://lkml.kernel.org/r/1332960678-11879-2-git-send-email-andi@firstfloor.org Signed-off-by: H. Peter Anvin <hpa@zytor.com>
-rw-r--r--Makefile10
-rw-r--r--lib/Kconfig.debug9
2 files changed, 19 insertions, 0 deletions
diff --git a/Makefile b/Makefile
index 1932984478c1..6f7328bca9c4 100644
--- a/Makefile
+++ b/Makefile
@@ -564,6 +564,16 @@ else
KBUILD_CFLAGS += -O2
endif
+ifdef CONFIG_READABLE_ASM
+# Disable optimizations that make assembler listings hard to read.
+# reorder blocks reorders the control in the function
+# ipa clone creates specialized cloned functions
+# partial inlining inlines only parts of functions
+KBUILD_CFLAGS += $(call cc-option,-fno-reorder-blocks,) \
+ $(call cc-option,-fno-ipa-cp-clone,) \
+ $(call cc-option,-fno-partial-inlining)
+endif
+
include $(srctree)/arch/$(SRCARCH)/Makefile
ifneq ($(CONFIG_FRAME_WARN),0)
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 6777153f18f3..4d3cbbbe4516 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -70,6 +70,15 @@ config STRIP_ASM_SYMS
that look like '.Lxxx') so they don't pollute the output of
get_wchan() and suchlike.
+config READABLE_ASM
+ bool "Generate readable assembler code"
+ depends on DEBUG_KERNEL
+ help
+ Disable some compiler optimizations that tend to generate human unreadable
+ assembler output. This may make the kernel slightly slower, but it helps
+ to keep kernel developers who have to stare a lot at assembler listings
+ sane.
+
config UNUSED_SYMBOLS
bool "Enable unused/obsolete exported symbols"
default y if X86