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[Xen-devel] Re: RFC: Using grant table to give iomem permission

To: Kieran Mansley <kmansley@xxxxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel] Re: RFC: Using grant table to give iomem permission
From: Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>
Date: Fri, 18 May 2007 15:05:55 +0100
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On 18/5/07 15:01, "Kieran Mansley" <kmansley@xxxxxxxxxxxxxx> wrote:

> When finished, the mapping domain can similarly unmap the grant, which
> removes its ability to ioremap() the page:
> struct gnttab_unmap_grant_ref op;
> gnttab_set_unmap_op(&op, 0, GNTMAP_iomem_map, handle);
> if (HYPERVISOR_grant_table_op(GNTTABOP_unmap_grant_ref, &op, 1))
> BUG();
> Some questions from me:
>  - does this approach seem sane?

There's no reason you shouldn't be able to use GNTMAP_host_map as usual, and
do refcounting in the active grant entry, also as usual.

 -- Keir

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