Re: [PATCH] arm64: remove redundant FRAME_POINTER kconfig option

Will Deacon
2015-11-06T16:19:00Z

On Fri, Nov 06, 2015 at 04:12:14PM +0000, Catalin Marinas wrote:
> On Fri, Nov 06, 2015 at 12:30:09PM +0000, Will Deacon wrote:
> > On Wed, Nov 04, 2015 at 09:37:51AM -0800, Yang Shi wrote:
> > > FRAME_POINTER is defined in lib/Kconfig.debug, it is unnecessary to redefine
> > > it in arch/arm64/Kconfig.debug.
> >
> > It might be worth noting that this adds a dependency on DEBUG_KERNEL
> > for building with frame pointers. I'm ok with that (it appears to be
> > enabled in defconfig and follows the vast majority of other archs) but
> > it is a change in behaviour.
>
> We shouldn't have the dependency on DEBUG_KERNEL since we select
> ARCH_WANT_FRAME_POINTERS on arm64. However, the patch would allow one to
> disable FRAME_POINTERS (not sure it has any effect on the aarch64 gcc
> though).

Ah yes, you're right about DEBUG_KERNEL. I completely misread the brackets
and the left-associativity of &&/|| works out.

I still think Rutland has a valid point wrt junk frame pointers, though.

Will