Messages in this thread | | | Subject | Re: [PATCH 03/10] ftrace: allow building without frame pointers | From | Steven Rostedt <> | Date | Sun, 14 Mar 2010 12:56:03 -0400 |
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On Sat, 2010-03-13 at 12:19 +0530, Rabin Vincent wrote: > With current gcc, compiling with both -pg and -fomit-frame-pointer is > not allowed. However, -pg can be used to build without actually > specying -fno-omit-frame-pointer, upon which the defaut behaviour for > the target will be used. > > On ARM, it is not possible to build a Thumb-2 kernel with > -fno-omit-frame-pointer (FRAME_POINTERS depends on !THUMB2_KERNEL). In > order to support ftrace for Thumb-2, we need to be able to allow a > combination of FUNCTION_TRACER and !FRAME_POINTER. We do this by > omitting -fomit-frame-pointer if ftrace is enabled. > > Acked-by: Frederic Weisbecker <fweisbec@gmail.com> > Signed-off-by: Rabin Vincent <rabin@rab.in> > --- > v2: Better comment. > > Makefile | 7 +++++++ > 1 files changed, 7 insertions(+), 0 deletions(-) > > diff --git a/Makefile b/Makefile > index 08ff02d..61404e0 100644 > --- a/Makefile > +++ b/Makefile > @@ -546,8 +546,15 @@ endif > ifdef CONFIG_FRAME_POINTER > KBUILD_CFLAGS += -fno-omit-frame-pointer -fno-optimize-sibling-calls > else > +# Some targets (ARM with Thumb2, for example), can't be built with frame > +# pointers. For those, we don't have FUNCTION_TRACER automatically > +# select FRAME_POINTER. However, FUNCTION_TRACER adds -pg, and this is > +# incompatible with -fomit-frame-pointer with current GCC, so we don't use > +# -fomit-frame-pointer with FUNCTION_TRACER. > +ifndef CONFIG_FUNCTION_TRACER > KBUILD_CFLAGS += -fomit-frame-pointer
I believe this is correct, but have you tested this on other archs other than ARM? I can do it for x86 and PPC, but it will need to wait as those machines are currently performing stress tests.
-- Steve
> endif > +endif > > ifdef CONFIG_DEBUG_INFO > KBUILD_CFLAGS += -g
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