[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Confusion about copy_to/from_guest
On Mon, Apr 26, 2010 at 11:03 AM, Keir Fraser <keir.fraser@xxxxxxxxxxxxx> wrote: > On 26/04/2010 03:32, "Tej" <bewith.tej@xxxxxxxxx> wrote: > >> Now passing the list_head from kernel using hypercall. Now how do I >> copy the element between kernel and hypervisor. >> >> 1. copy_from_guest(hyp_list_head, arg, 1) or >> copy_from_guest(hyp_list_head, arg, <num_of_elements_list>) >> 2. copy_to_guest(arg, hyp_list_head, 1) or copy_to_guest(arg, >> hyp_list_head, <num of element in list>) > > The first of these. Copy_{to,from}_guest can copy arrays of structures, but > since this is a linked structure you'd have to do the copy one element at a > time. you mean to say, in hypervisor space copy first element using copy_from_guest(hyp_list_head, arg, 1), extract the next address from it and then copy again the next element using "copy_from_guest(hyp_list_head->next, arg->next, 1)" ??? > >> 2nd question: >> I did first one, but first element of list was not accessible in >> hypervisor space, why? > > Well, if you are really only copying the list_head, the above should work. Yes, I have carried out the sample test, by allocating small struct linked list and then passing between hypervisor and kernel copy_from_guest(hyp_list_head, arg, 1) is working correctly. But my actial code is not working. Ok let me put some more effort, if not I will push the code for review. Thanks for your help > > -- Keir > > > _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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