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Re: RFC: Sentosa boot fix

To: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Subject: Re: RFC: Sentosa boot fix
From: "Maciej W. Rozycki" <macro@linux-mips.org>
Date: Tue, 30 Jan 2007 17:33:02 +0000 (GMT)
Cc: dan@debian.org, vagabon.xyz@gmail.com, linux-mips@linux-mips.org, ralf@linux-mips.org
In-reply-to: <20070130.234537.126574565.anemo@mba.ocn.ne.jp>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <cda58cb80701290806p5d68ba5ck5e3e3b2b3490126f@mail.gmail.com> <20070129161450.GA3384@nevyn.them.org> <Pine.LNX.4.64N.0701291833480.26916@blysk.ds.pg.gda.pl> <20070130.234537.126574565.anemo@mba.ocn.ne.jp>
Sender: linux-mips-bounce@linux-mips.org
On Tue, 30 Jan 2007, Atsushi Nemoto wrote:

> Though I do not object to remove "&& !defined(CONFIG_BUILD_ELF64)"
> from __pa_page_offset(), are there any point of CONFIG_BUILD_ELF64=y
> if your load address was CKSEG0?

 Checking for code correctness and validation of the toolchain (Linux is 
one of the few non-PIC users of (n)64) without having to chase hardware 
that would support running from XPHYS without serious pain (the firmware 
being the usual offender).

 That said, I have not checked the every single use of __pa_page_offset(), 
but the sole existence of this condition raises a question about whether 
we are sure __pa_page_offset() is going to be only used on virtual 
addresses in the same segment the kernel is linked to.  Sometimes 
references to both CKSEG0 and XPHYS may be used in the same kernel, e.g. 
because the the kernel is linked to XPHYS, but the firmware is limited to 
accept CKSEG0 addresses only (and we do call back into firmware on some 
platforms).

  Maciej

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