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Message-ID: <47FB8751.3040301@ru.mvista.com>
Date: Tue, 08 Apr 2008 18:55:13 +0400
From: Sergei Shtylyov <sshtylyov@...mvista.com>
To: Tejun Heo <htejun@...il.com>
Cc: jgarzik@...ox.com, gregkh@...e.de, alan@...rguk.ukuu.org.uk,
linux-kernel@...r.kernel.org, linux-ide@...r.kernel.org,
linuxppc-dev@...abs.org
Subject: Re: [PATCH 6/13] devres: implement managed iomap interface
Tejun Heo wrote:
>> A very late comment but nevertheless... :-)
> Better late than never.
:-)
>> Those functions are going to break on 32-bit platforms with
>> extended physical address (well, that's starting with Pentiums which
>> had 36-bit PAE :-) AND devices mapped beyond 4 GB (e.g. PowerPC 44x).
>> You should have used resource_size_t for the 'offset' parameter. As
>> this most probably means that libata is broken on such platforms, I'm
>> going to submit a patch...
It's broken with drivers using MMIO, I meant to say.
> Yeah, right please go ahead. But I wonder whether any BIOS was actually
> crazy enough to map mmio region above 4G on 32bit machine.
This is a *hardware* mapping on some non-x86 platforms (like PPC 44x or
MIPS Alchemy). The arch/ppc/ and arch/mips/ kernels have special hooks called
from ioremap() which help create an illusion that the PCI memory space on such
platforms (not only it) is mapped below 4 GB; arch/powerpc/ kernel doesn't do
this anymore -- hence this newly encountered issue.
WBR, Sergei
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