Re: [discuss] [PATCH] allow CONFIG_FRAME_POINTER for x86-64

[Andi Kleen <ak@suse.de>]

On Fri, Sep 09, 2005 at 12:14:38PM +0100, Hugh Dickins wrote:
> 
> Ah, right.  I'm using kdb with it.  (And my recollection of when
> show_stack did have a framepointer version, is that it was hopelessly
> broken on interrupt frames, and we're much better off without it.)

Not sure if the x86-64 kdb had code to follow them either.
The i386 one has.


> 
> > The only reason to use them would be external debuggers, but those
> > don't need them on x86-64 neither.
> 
> Don't need them, but find them as useful on x86_64 as on i386?
> 
> Certainly, I can go on patching in FRAME_POINTERs for x86_64
> as I have done, no problem with that.  But it seems both bogus
> and unhelpful to have that "&& !X86_64" in lib/Kconfig.debug -
> framepointers are as helpful/useless on x86_64 as the rest.

The original reason was that they were never enabled because
nobody passed -fno-omit-frame-pointer. That was apparently
later fixed.

But kdb should be using a dwarf2 unwinder instead. kgdb certainly
supports that, as does NLKD.

-Andi