Re: [Xen-devel] Sharing grant_table pages between 2 miniOS

[Kieran Mansley <kmansley@xxxxxxxxxxxxxx>]

On Mon, 2007-05-14 at 20:34 -0700, Lamia M. Youseff wrote:
> Dear All,
> I am doing a small experiment with grant table to share 4 pages of 
> memory between 2 miniOS, but have not been successful. For some reason, 
> my GNTTABOP_map_grant_ref returns -1

Is it possible that the grant_operation_permitted() call during the
map_grant_ref operation is failing?  The code in question is this (from
include/xen/iocap.h):

/*
 * Until TLB flushing issues are sorted out we consider it unsafe for
 * domains with no hardware-access privileges to perform grant
map/transfer
 * operations.
 */
#define grant_operation_permitted(d)                    \
    (!rangeset_is_empty((d)->iomem_caps))

If this is the case, giving the granting domain some iomem capability
should allow you to do what you want.  I'm not sure what the TLB
flushing issues are, or what the plan is to get a proper solution to
this.

Kieran



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