Re: [Xen-devel] about: XENMEM_machphys_mfn_list

To:	"BVK Chaitanya" <bayapuneni_chaitanya@xxxxxxxxxxxx>
Subject:	Re: [Xen-devel] about: XENMEM_machphys_mfn_list
From:	Lin.Yu <yulin724@xxxxxxxxx>
Date:	Fri, 18 Jul 2008 17:22:26 +0800
Cc:	Xen-devel@xxxxxxxxxxxxxxxxxxx
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Got it.
But why 2MB? I have no any clue about it.

-- Lin

On Fri, Jul 18, 2008 at 5:10 PM, BVK Chaitanya <bayapuneni_chaitanya@xxxxxxxxxxxx> wrote:

Lin.Yu wrote:

XENMEM_machphys_mfn_list command is used to acquire the mapping between the pseudo-physical to machine. And the hypercall will fill in the struct xen_machphys_mfn_list.

I do not understand "This table is an array of pseudo-physical frame numbers of the start of 2MB extents, corresponding to 2MB rangs in the pseudo-physical address space".
"This table" means the array pointed by xen_machphys_mfn_list.extent_start.

I am reading the code about this struct, still in confusion.
:-)
Who can help me?

AFAIU, here "table" is nothing more than an array of xen_pfn_ts.

Only complication is, mfns returned are `base-mfns' for 2MB memory regions.

For example, if mfn 100 is returned, it means mfns 100-612 hold the 2MB region (612 = 100 + 512; 512 pages make 2MB)

--
bvk-chaitanya

--
Best Regards,
-- Lin.Yu

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Re: [Xen-devel] about: XENMEM_machphys_mfn_list