kbuild: move -fno-dwarf2-cfi-asm to powerpc only

Better dwarf2 unwind information is a good thing, it allows better
debugging with kgdb and crash and helps systemtap.

Commit 003086497f07f7f1e67c0c295e261740f822b377 ("Build with
-fno-dwarf2-cfi-asm") disabled some CFI information globally to work
around a module loader bug on powerpc.

But this disables the better unwind tables for all architectures, not just
powerpc.  Move the workaround to powerpc and also add a suitable comment
that's it really a workaround.

This improves dwarf2 unwind tables on x86 at least.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Michal Marek <mmarek@suse.cz>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
index 1a54a3b3a3fa..42dcd3f4ad7b 100644
--- a/arch/powerpc/Makefile
+++ b/arch/powerpc/Makefile
@@ -112,6 +112,11 @@ KBUILD_CFLAGS += $(call cc-option,-mspe=no)
 # kernel considerably.
 KBUILD_CFLAGS += $(call cc-option,-funit-at-a-time)
 
+# FIXME: the module load should be taught about the additional relocs
+# generated by this.
+# revert to pre-gcc-4.4 behaviour of .eh_frame
+KBUILD_CFLAGS   += $(call cc-option,-fno-dwarf2-cfi-asm)
+
 # Never use string load/store instructions as they are
 # often slow when they are implemented at all
 KBUILD_CFLAGS           += -mno-string