kbuild: move -fno-dwarf2-cfi-asm to powerpc only (d0679c73) · Commits · 戴 / test

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

Makefile

+0 −3

Original line number	Diff line number	Diff line
		@@ -579,9 +579,6 @@ KBUILD_CFLAGS += $(call cc-option,-Wno-pointer-sign,)
		# disable invalid "can't wrap" optimizations for signed / pointers
		KBUILD_CFLAGS += $(call cc-option,-fno-strict-overflow)

		# revert to pre-gcc-4.4 behaviour of .eh_frame
		KBUILD_CFLAGS += $(call cc-option,-fno-dwarf2-cfi-asm)

		# conserve stack if available
		KBUILD_CFLAGS += $(call cc-option,-fconserve-stack)

arch/powerpc/Makefile

+5 −0

Original line number	Diff line number	Diff line
		@@ -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

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