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From: Sergei Shtylyov <sshtylyov@ru•mvista.com>
To: Tejun Heo <htejun@gmail•com>
Cc: linux-ide@vger•kernel.org, gregkh@suse•de,
	linux-kernel@vger•kernel.org, linuxppc-dev@ozlabs•org,
	jgarzik@pobox•com, alan@lxorguk•ukuu.org.uk
Subject: Re: [PATCH 6/13] devres: implement managed iomap interface
Date: Thu, 10 Apr 2008 20:56:12 +0400	[thread overview]
Message-ID: <47FE46AC.5000901@ru.mvista.com> (raw)
In-Reply-To: <47FB8751.3040301@ru.mvista.com>

Hello, I wrote:

>>>    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.

    Oops, I meant PCI drivers here, at least for the time being. And it looks 
like that was a false alarm. :-]

>> 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.

    I thought that pcim_iomap() used devm_ioremap() or something -- which of 
course turned to be wrong. devm_ioremap() alone is yet safe since there are no 
users for it amongst PPC 44x platform device drivers...

MBR, Sergei

  parent reply	other threads:[~2008-04-10 16:56 UTC|newest]

Thread overview: 9+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <11684073371547-git-send-email-htejun@gmail.com>
2008-04-07 16:46 ` [PATCH 6/13] devres: implement managed iomap interface Sergei Shtylyov
2008-04-08 14:48   ` Tejun Heo
2008-04-08 14:55     ` Sergei Shtylyov
2008-04-08 15:03       ` Tejun Heo
2008-04-10 16:56       ` Sergei Shtylyov [this message]
2008-04-10 17:44         ` Kumar Gala
2008-04-10 18:24           ` Sergei Shtylyov
2008-04-10 19:40             ` Kumar Gala
2008-04-11  2:08               ` Tejun Heo

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