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Date:	Mon, 9 Oct 2006 14:21:32 +0100
From:	Thiemo Seufer <ths@networkno.de>
To:	Franck Bui-Huu <vagabon.xyz@gmail.com>
Cc:	Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
Subject: Re: [PATCH] setup.c: introduce __pa_symbol() and get ride of CPHYSADDR()
Message-ID: <20061009132131.GA18308@networkno.de>
References: <45265BF0.8080103@innova-card.com> <20061006172153.GB4456@networkno.de> <452A3953.4060802@innova-card.com>
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Franck Bui-Huu wrote:
> Thiemo Seufer wrote:
> > Franck Bui-Huu wrote:
> >>
> >> -	if (CPHYSADDR(initrd_end) > PFN_PHYS(max_low_pfn)) {
> >> +	if (__pa(initrd_end) > PFN_PHYS(max_low_pfn)) {
> > 
> > ISTR this failed on O2, where kernel+initrd are loaded into KSEG0 but the
> > PAGE_OFFSET is for XKPHYS.
> > 
> 
> I guess that you were meaning somthing like:
> 
> LOADADDR    = 0xffffffff80004000
> PAGE_OFFSET = 0xa800000000000000
> 
> is that correct ?

Yes.

> If so could you explain the choice of these values
> because I fail to understand it.

It allows to load a 64-bit kernel in KSEG0, and use short 2-instruction
symbol references there. At the same time, it allows access to more
address space for memory and I/O than would fit in KSEG0.


Thiemo