Xen devel - Jul 2008 - question about mapping memory from Dom0 to domU

Hi:
    I wanna write code about sharing memory between dom0 and domU, and I decide
to use void *xc_map_foreign_range(int xc_handle, unint32_t dom, int size, int
port, unsigned long mfn) (this is a function in xenctl.h).
   My question is :
   If I wanna map a range of memory in dom0 to domU, how can I　get the value of
mfn? and I do not know the port here.

   Can anybody help me ?
   Thanks .


                                                                Danius Wu
========================================================
 
 


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you can use xc_translate_foreign_address to get a the mfn of a give virtual
address

2008/7/9 吴佳民 <wujiamin_tyut@163.com>:
>  Hi:
>     I wanna write code about sharing memory between dom0 and domU, and I
> decide to use void *xc_map_foreign_range(int xc_handle, unint32_t dom, int
> size, int port, unsigned long mfn) (this is a function in xenctl.h).
>    My question is :
>    If I wanna map a range of memory in dom0 to domU, how can I get the
> value of mfn? and I do not know the port here.
>
>    Can anybody help me ?
>    Thanks .
>
>
>                                                                 Danius Wu
> ========================================================>
>
>
>
>
> ------------------------------
> 渊波阔宅 湖景人生 <http://popme.163.com/link/003984_0707_2982.html>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
>

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Hi,

This won't work: xc_map_foreign_range can only be used in privileged
domains (i.e. Dom0) to map memory from DomUs. This is because allowing
a DomU to map arbitrary memory from another domain would undermine the
security and isolation of the system.

You could use xc_map_foreign_range in Dom0 to map memory from the
DomU. However, it would be better still to use grant references, as
this would observe the principle of least privilege.

Note also that the parameter "port" is actually "prot",
which
corresponds to the page-protection on the mapped pages (e.g.
PROT_READ, or PROT_READ | PROT_WRITE).

Regards,

Derek Murray.

2008/7/10 吴佳民 <wujiamin_tyut@163.com>:
>  Hi:
>     I wanna write code about sharing memory between dom0 and domU, and I
> decide to use void *xc_map_foreign_range(int xc_handle, unint32_t dom, int
> size, int port, unsigned long mfn) (this is a function in xenctl.h).
>    My question is :
>    If I wanna map a range of memory in dom0 to domU, how can I　get the
value
> of mfn? and I do not know the port here.
>
>    Can anybody help me ?
>    Thanks .
>
>
>                                                                 Danius Wu
> ========================================================>
>
>
>
> ________________________________
> 渊波阔宅 湖景人生
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel
>
>
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