[Xen-devel] RE: One question to compat model

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

>-----Original Message-----
>From: Keir Fraser [mailto:keir.fraser@xxxxxxxxxxxxx]
>Sent: Thursday, May 13, 2010 4:48 PM
>To: Jiang, Yunhong; Jan Beulich
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: Re: One question to compat model
>
>On 13/05/2010 09:41, "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> wrote:
>
>>> Whoever implemented XENPF_getidletime decided to stuff a fake xenctl_cpumap
>>> struct within Xen rather than properly refactor the public headers. There's
>>> no reason not to move xenctl_cpumap out into xen.h.
>>
>> A curios question. I checked the code, and notice that the
>XEN_GUEST_HANDLE_64
>> is only defined for __XEN__ or __XEN_TOOLS__. I can understand it is needed
>> for tools because 32bit tools can be used in 64bit dom0, but why it is
>> forbidden for kernel? To avoid it be passed as hypercall parameter? Sorry for
>> bothering if this is a stupid question :$
>
>I was probably being overzealous. There's no good reason not to use
>GUEST_HANDLE_64 and uint64_aligned_t outside of tools interfaces.

Althoug not related with my current patch, but curiosly, will it avoid the 
compat model issue if we use XEN_GUEST_HANDLE_64 for hypercall, especially if 
not performance critical, like struct xen_mc_fetch? (Maybe we still need 
consider the #pragma pack optoin for the struction?)

--jyh

>
> -- Keir
>


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