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From: Paul Mackerras <paulus@samba.org>
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Date: Thu, 3 Jan 2002 10:11:53 +1100 (EST)
To: Tom Rini <trini@kernel.crashing.org>
Cc: Momchil Velikov <velco@fadata.bg>, linux-kernel@vger.kernel.org,
        gcc@gcc.gnu.org, linuxppc-dev@lists.linuxppc.org,
        Franz Sirl <Franz.Sirl-kernel@lauterbach.com>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Corey Minyard <minyard@acm.org>
Subject: Re: [PATCH] C undefined behavior fix
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Tom Rini writes:

> Okay, here's a summary of all of the options we have:
> 1) Change this particular strcpy to a memcpy
> 2) Add -ffreestanding to the CFLAGS of arch/ppc/kernel/prom.o (If this
> optimization comes back on with this flag later on, it would be a
> compiler bug, yes?)
> 3) Modify the RELOC() marco in such a way that GCC won't attempt to
> optimize anything which touches it [1]. (Franz, again by Jakub)
> 4) Introduce a function to do the calculations [2]. (Corey Minyard)
> 5) 'Properly' set things up so that we don't need the RELOC() macros
> (-mrelocatable or so?), and forget this mess altogether.

I would add:

6) change strcpy to string_copy so gcc doesn't think it knows what the
   function does
7) code RELOC etc. in assembly, which would let us get rid of the
	offset = reloc_offset();
   at the beginning of each function which uses RELOC.

Maybe 7 is the way to go, at least it will shut the bush-lawyers up.

Paul.
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