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

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Message-ID: <4D54EB6A.3010405@jp.fujitsu.com>
Date:	Fri, 11 Feb 2011 16:55:22 +0900
From:	Kenji Kaneshige <kaneshige.kenji@...fujitsu.com>
To:	TAKADA Yoshihito <takada@....nifty.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 don't know what version of kernel you're using. But I guess you
might also need 4302e0fb7fa5b071e30f3cfb68e85155b3d69d9b (PCI: fix
wrong memory address handling in MSI-X).

Regards,
Kenji Kaneshige

(2011/02/10 23:11), TAKADA Yoshihito wrote:
> 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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