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Re: [Xen-devel] Grant Tables & mm.c

On 7 Jul 2007, at 14:44, Koripella Srinivas wrote:

I was looking at the user space grant tables but i did not find any code calling the function "remap_pfn_range" to map the kmalloc ed allocated memory into user space.
What could be the reason?? Or am i missing something

The mapping takes place in drivers/xen/gntdev/gntdev.c, in the function gntdev_mmap(). In the normal case (no shadow page tables), the page is mapped into user space by calling HYPERVISOR_grant_table_op, with the GNTTABOP_map_grant_ref operation, and (amongst other things) a pointer to the page table entry to be rewritten. Therefore, it is not necessary to call remap_pfn_range().

I'm not sure what you mean by "the kmalloc ed allocated memory". The memory is allocated by another domain, and inserted in the grant table. In the kernel that carries out the mapping, kmalloc is used only for allocating kernel-private data structures.

Regards,

Derek Murray.

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