Re: [PATCH 2/4] x86: ioremap: fix physical address check

From: Kenji Kaneshige
Date: Mon Jun 14 2010 - 04:28:16 EST

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.

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.

Kenji Kaneshige

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