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Date: Mon, 14 Jun 2010 18:02:59 +0900
From: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
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To: "Maciej W. Rozycki" <macro@linux-mips.org>
CC: "H. Peter Anvin" <hpa@zytor.com>, Thomas Gleixner <tglx@linutronix.de>,
       Ingo Molnar <mingo@redhat.com>, linux-kernel@vger.kernel.org,
       linux-pci@vger.kernel.org, jbarnes@virtuousgeek.org
Subject: Re: [PATCH 2/4] x86: ioremap: fix physical address check
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(2010/06/14 17:23), Kenji Kaneshige wrote:
> (2010/06/14 15:38), Maciej W. Rozycki wrote:
>> On Mon, 14 Jun 2010, Kenji Kaneshige wrote:
>>
>>> - Architectural limit of physical address in x86 32-bit mode is 40-bit
>>> (depnds on processor version).
>>
>> According to documentation I happen to have handy this limit is actually
>> 52 bits (and space is currently available in the data structures used for
>> a possible future extension up to 63 bits).
>
> Thank you for pointing it out. I misunderstood that.
>
> Now I think I need to add additional check to see if specified
> physical address can be handled by x86 ioremap(), instead of
> changing phys_addr_valid(). The code would be
>
> static void __iomem *__ioremap_caller(...)
> {
> ...
> #if defined(CONFIG_X86_32) && defined(CONFIG_X86_PAE)
> if (phys_addr is higer than 36-bit) {
> printk(KERN_INFO "ioremap can't map physical address %llx\n",
> return NULL;
> }
> #endif
> ...
> }

Please ignore above again. Sorry for inconvenient.
According to the comment from H. Peter Anvin, 36-bit limit is on
RAM in 32-bit mode. So this approach is wrong.

Now I guess there is a bug that doesn't handle physical address
higher than 32-bit properly somewhere...

Thanks,
Kenji Kaneshige