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Message-ID: <452D180D.9020700@innova-card.com>
Date:	Wed, 11 Oct 2006 18:13:01 +0200
Reply-To: Franck <vagabon.xyz@gmail.com>
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To:	Atsushi Nemoto <anemo@mba.ocn.ne.jp>
CC:	vagabon.xyz@gmail.com, ralf@linux-mips.org, ths@networkno.de,
	linux-mips@linux-mips.org
Subject: Re: [PATCH 4/5] Introduce __pa_symbol()
References: <1160568525897-git-send-email-fbuihuu@gmail.com>	<11605685254080-git-send-email-fbuihuu@gmail.com> <20061012.003436.130240259.anemo@mba.ocn.ne.jp>
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From:	Franck Bui-Huu <vagabon.xyz@gmail.com>
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Atsushi Nemoto wrote:
> On Wed, 11 Oct 2006 14:08:44 +0200, Franck Bui-Huu <vagabon.xyz@gmail.com> wrote:
>> This patch introduces __pa_symbol() macro which should be used to
>> calculate the physical address of kernel symbols. It also relies
>> on RELOC_HIDE() to avoid any compiler's oddities when doing
>> arithmetics on symbols.
> 
> I agree with you that we need __pa_symbol(), but what is a purpose of
> using RELOC_HIDE() here?  Frankly I do not understand what
> RELOC_HIDE() does...
> 

RELOC_HIDE(x) is used because arithmetic on symbol addresses is
undefined in C language. It avoid gcc to know that:

	RELOC_HIDE(&_end) + OFFSET

is an operation on a symbol address and thus avoid an undefined
operation.

		Franck