[PATCH 2/2] Kbuild: Add a option to enable dwarf4

Andi Kleen
2014-07-29T23:12:40Z

From: Andi Kleen <ak@linux.intel.com>

I found that a lot of unresolvable variables when using gdb on the kernel
become resolvable when dwarf4 is enabled. So add a Kconfig flag to enable it.

It definitely increases the debug information size, but on the other
hand this isn't so bad when debug fusion is used.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
---
Makefile | 3 +++
lib/Kconfig.debug | 9 +++++++++
2 files changed, 12 insertions(+)

diff --git a/Makefile b/Makefile
index 6a717cd..6cdf3f0 100644
--- a/Makefile
+++ b/Makefile
@@ -696,6 +696,9 @@ KBUILD_CFLAGS += -g
endif
KBUILD_AFLAGS += -Wa,-gdwarf-2
endif
+ifdef CONFIG_DEBUG_INFO_DWARF4
+KBUILD_CFLAGS += -gdwarf-4
+endif

ifdef CONFIG_DEBUG_INFO_REDUCED
KBUILD_CFLAGS += $(call cc-option, -femit-struct-debug-baseonly) \
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 0360468..a2dcf97 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -158,6 +158,15 @@ config DEBUG_INFO_SPLIT
to know about the .dwo files and include them.
Incompatible with older versions of ccache.

+config DEBUG_INFO_DWARF4
+ bool "Generate dwarf4 debuginfo"
+ depends on DEBUG_INFO
+ help
+ Generate dwarf4 debug info. This requires recent versions
+ of gcc and gdb. It makes the debug information larger.
+ But it significantly improves the success of resolving
+ variables in gdb on optimized code.
+
config ENABLE_WARN_DEPRECATED
bool "Enable __deprecated logic"
default y
--
1.8.5.2