linux-kernel - Re: [BUG][PATCH 0/2 (v.3)] x86: ioremap() problem in X86

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Date:	Thu, 10 Feb 2011 23:11:24 +0900
From:	TAKADA Yoshihito <takada@....nifty.com>
To:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
Cc:	hpa@...or.com, tglx@...utronix.de, mingo@...hat.com,
	linux-kernel@...r.kernel.org, matthew@....cx, macro@...ux-mips.org,
	kamezawa.hiroyu@...fujitsu.com, eike-kernel@...tec.de,
	jeremy@...p.org, linux-pci@...r.kernel.org
Subject: Re: [BUG][PATCH 0/2 (v.3)] x86: ioremap() problem in X86_32 PAE

Hi.
I faced same probrem, too. I use x86_64 kernel.
Your patch fix it. it's very effective.
Thanks!

2010年6月18日12:21 Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>:
> Hi,
>
> Here is a updated version (v.3) of patchset to fix ioremap() related
> problem found in x86 32-bit mode. The problem is that ioremap() maps
> wrong address for the device to which phisical addres higer than
> 32-bit is assigned (ioat device in my case).
>
> The v.3 patches are:
>
> - [PATCH 1/2] x86: ioremap: fix wrong physical address handling
> - [PATCH 2/2] x86: ioremap: fix normal ram range check
>
> Changelog
> ---------
> v.2=>v.3:
> - Matthew Wilcox suggested changing PAGE_MASK definition. But I think
>  it is a little risky. Instead of changing PAGE_MASK, v.3 patch uses
>  PHYSICAL_PAGE_MASK(*) to mask physical address again, as v.1 patch
>  did. The PHYSICAL_PAGE_MASK doesn't work for higher than 2^44
>  physical address because __PHYSICAL_MASK_SHIFT is 44 in x86_32
>  PAE(*). But this time, I focus on making 2^44 work correctly.
>
> (*) Current X86_32 PAE kernel would not work with physical address
>    higher than 2^44, because PFNs are handled using 32-bit variable
>    (unsigned long) probably in many places. This seems the reason why
>    __PHYSICAL_MASK_SHIFT is limited to 44 (=32+12 is the limit we can
>    fit into an unsigned long pfn). When x86 PAE linux becomes above
>    2^44 physical address capable in someday, __PHYSICAL_MASK_SHIFT
>    should become greater value than 44.
>
>
> v.1=>v.2:
> The v.1 patchset was based on my misunderstanding about architectural
> limit and linux memory management limit of physical address. So some
> patches in v.1 were totally wrong fixes and they are removed. Thanks
> to the feedbacks for v.1 patchset, it turned out that phsical address
> is handled improperly (higher 32-bits are cleared unexpectedly) also
> in the other places than where v.1 patchset fixed. Here are summary of
> changes.
>
> - Stop using PHYSICAL_PAGE_MASK to align physical address because
>  PHYSICAL_PAGE_MASK would not work if physical address is higher than
>  44-bit.
> - Fix remaining bugs of physical address handling in ioremap() code
>  path according to the feedbacks.
> - Fix s_show() in vmalloc.c to show high physical address properly.
> - Removed changes against phys_addr_valid() ([PATCH 2/4] in v.1).
> - Removed changes against warning message in ioremap() ([PATCH 3/4] in
>  v.1).
>
> Thanks,
> Kenji Kaneshige
>
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