From: Andi Kleen <ak@suse.de>
To: discuss@x86-64.org
Subject: Re: [discuss] [PATCH] allow CONFIG_FRAME_POINTER for x86-64
Date: Fri, 9 Sep 2005 13:42:12 +0200
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Cc: Hugh Dickins <hugh@veritas.com>, Jan Beulich <JBeulich@novell.com>,
       linux-kernel@vger.kernel.org
References: <43207D28020000780002451E@emea1-mh.id2.novell.com> <20050909112108.GK19913@wotan.suse.de> <Pine.LNX.4.61.0509091222310.6443@goblin.wat.veritas.com>
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On Friday 09 September 2005 13:31, Hugh Dickins wrote:
> On Fri, 9 Sep 2005, Andi Kleen wrote:
> > 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.
>
> x86_64 kdb does have the code to follow them, it's pretty much the same.

It will not work very well because the interrupt/exception etc. code makes
no attempt to preserve the frame. So it's a bad hack at best.

> > But kdb should be using a dwarf2 unwinder instead. kgdb certainly
> > supports that, as does NLKD.
>
> In an ideal and bloat-neutral world.  I've always imagined it to be
> quite a lot of work, bringing in its own set of problems: but great
> that that work has now been done, and yes, it might one day get
> ported to kdb.  But removing "&& !X86_64" is much easier.

Hmm ok. I will do that change.

-Andi
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