RE: [Xen-devel] Question on xc_gnttab_map_grant_ref()

["King, Steven R" <steven.r.king@xxxxxxxxx>]

I've been looking at xc_gnttab stuff lately too and the current
implementation is incomplete.  For example, I don't see a way to acquire
a grant reference from user space, so the xc_gnttab functions taking a
reference are unusable.

IMO, grant references are kernel level implementation details that
should not be exposed to user-mode anyway.  Instead, user-mode needs
IOCTLs to share pages with a remote domain and to map those shared pages
within the remote end.  If the kernel implements this functionality with
grant tables, then great; in the future it may do something else.  I
hope to have a patch to offer for this eventually.

-steve


-----Original Message-----
From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of NAHieu
Sent: Thursday, November 03, 2005 4:53 AM
To: xen-devel
Subject: [Xen-devel] Question on xc_gnttab_map_grant_ref()

Hi,

I am writing a kermel module in DomU, and this module grants a page of
memory to Dom0. Then in Dom0 I try to grant_map it with
xc_gnttab_map_grant_ref()

But this function requires a flag, and I don't know which option to give
it. I tried with either GNTMAP_application_map or
GTF_reading|GTF_writing, but I always got this error:

ERROR: do_gnttab_op: HYPERVISOR_grant_table_op failed: -1

Anybody please tell me how to use xc_gnttab_map_grant_ref() properly in
Dom0's userspace?


Many thanks.
Hieu

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