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RE: [Xen-devel] Call hypercall straightly from user space

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] Call hypercall straightly from user space
From: "Xu, Anthony" <anthony.xu@xxxxxxxxx>
Date: Sun, 31 Dec 2006 12:30:21 +0800
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, xen-ia64-devel <xen-ia64-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] Call hypercall straightly from user space
Keir Fraser write on 2006年12月30日 20:30:
> On 30/12/06 11:27 am, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx> wrote:
>> That being the case, perhaps you need a
>> well-defined register-based ABI for all ia64 hypercalls (e.g., first
>> N bytes of the first pointer-passed structs/values passed to a
>> hypercall are re-packed into a subset of the IA64's register space).
>> The disadvantage here is the need for IA64-specific repacking on the
>> Xen and the guest sides of the hypercall interface, unless we could
>> think of some very cunning way to avoid it.
> Another option would be for the guest user space to know the
> virt->machine mapping for some of its address space, and use that as
> a pool to allocate hypercall buffers from. Then user space could fill
> in the xencomm descriptors for itself.
> This would need special allocation in libxc for hypercall buffers
> (since they would need to come from a pinned pool of memory for which
> libxc knows the v->m mapping) but we want to add this anyway, even
> for x86 (to reduce number of mlock/munlock calls we make).

Thanks for your suggestions.
I would like to add another wrapper for some hypercalls, 
And after hypercall buffer is implemented, then I'll follow it.


>  -- Keir

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