linux-kernel - Re: [PATCH] x86: remove __phys_reloc

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Date:	Mon, 09 Aug 2010 15:40:31 +0900
From:	Namhyung Kim <namhyung@...il.com>
To:	Andi Kleen <andi@...stfloor.org>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] x86: remove __phys_reloc_hide

2010-08-09 (월), 08:22 +0200, Andi Kleen:

> It's for the benefit of the compiler, we've had miscompilations
> due to undefined overflow for addresses in the past. The optimizer
> assumes this won't happen.
> 
> Given the x86-64 version normally doesn't overflow, but it's
> still safer to have it.
> 
> -Andi
> 

Hi, 

I'm not talking about the RELOC_HIDE itself. I do know we need it for
some specific case, ie. percpu. But in this case __pa_symbol(x) is
expanded to RELOC_HIDE((unsigned long)(x), 0) which does nothing
meaningful. I believe the overflow is not a concern here.

-- 
Regards,
Namhyung Kim


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