Message-ID: <4C15E7F4.9090607@jp.fujitsu.com>
Date: Mon, 14 Jun 2010 17:27:32 +0900
From: Kenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
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To: "H. Peter Anvin" <hpa@zytor.com>
CC: 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
References: <4C11FF10.4060203@jp.fujitsu.com> <4C11FFC0.1030006@jp.fujitsu.com> <4C1275BF.3070605@zytor.com> <4C158BCF.6000303@jp.fujitsu.com>
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> Do you mean x86 linux can map physical address higher than 36-bit for I/O?
> My understanding is as follows.
> - Architectural limit of physical address in x86 32-bit mode is 40-bit
> (depnds on processor version).
> - The maximum physical address supported by current x86 linux kernel in
> 32-bit mode is 36-bit.
> On my environment, physical address higher than 40-bit (ex. 0xfc00001c000)
> is assigned to some PCI devices. I think there is no way to handle such
> high physical address in 32-bit mode.
>
> Thanks,
> Kenji Kaneshige

Please ignore above. I misunderstood the architectural limit of physical
address in x86 32-bit mode. It is not 40-bits, but 52-bits.

Thanks,
Kenji Kaneshige

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