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[Xen-devel] one question to p2m table entry type

To: "tim.deegan@xxxxxxxxxx" <tim.deegan@xxxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: [Xen-devel] one question to p2m table entry type
From: "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>
Date: Wed, 5 May 2010 16:17:53 +0800
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Thread-topic: one question to p2m table entry type
Tim/Keir, I noticed that when translatiing p2m table type and p2m pte entry 
flags, there are difference handling for x86_64 and x32 like:

in p2m_type_to_flags:
#ifdef __x86_64__
    flags = (unsigned long)(t & 0x3fff) << 9;
    flags = (t & 0x7UL) << 9;

in p2m_flags_to_type:
    /* Type is stored in the "available" bits */
#ifdef __x86_64__
    return (flags >> 9) & 0x3fff;
    return (flags >> 9) & 0x7;

But since we don't support pure 32 bit xen hypervisor any more, and for 32 PAE, 
we are sure have enough bit to keep these flags, why do we need these special 
handling? Are there any special reason for it?


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