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[Xen-devel] RE: /dev/mem and /dev/kmem

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: [Xen-devel] RE: /dev/mem and /dev/kmem
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Wed, 21 Mar 2007 20:35:43 +0800
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Thread-topic: /dev/mem and /dev/kmem
>From: Keir Fraser [mailto:Keir.Fraser@xxxxxxxxxxxx]
>Sent: 2007年3月21日 18:08
>
>> Based on different interfaces used by /dev/mem and /dev/kmem
>> (direct_remap_pfn_range for former, and remap_pfn_range for the
>> latter), could I think that /dev/mem is the interface for dom0 to map
>> machine memory directly, while /dev/kmem is still geared to dom0's
>> own memory? If yes, then I may understand how Xserver can map
>> VGABIOS and why DOMID_IO is used for /dev/mem... :-)
>
>Yes, that's about right.
>
> -- Keir

So how about applications which simply use /dev/mem to map 
normal domain memory? Seems this breaks compatibility 
in user level though desired for above Xserver case... Or such 
case is rare?

BTW, I didn't find code to protect Xen to be mapped in this path, 
like in get_page_from_l1e(). Could you help pointing out?

Thanks,
Kevin

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