From mboxrd@z Thu Jan  1 00:00:00 1970
From: Samuel Thibault <samuel.thibault@eu.citrix.com>
Subject: Re: Running netback/blkback in non-dom0 domains
Date: Mon, 21 Jul 2008 19:19:52 +0100
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	<200807180030.48315.mark.williamson@cl.cam.ac.uk>
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To: Anton Burtsev <aburtsev@flux.utah.edu>
Cc: xen-devel@lists.xensource.com, Mark Williamson <mark.williamson@cl.cam.ac.uk>
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Anton Burtsev, le Mon 21 Jul 2008 12:11:37 -0600, a =E9crit :
>   2) If you export a block device from dom0 through a domU to the secon=
d=20
>      domU, e.g.
>     =20
>        /dev/loop0  ---->  /dev/sda2  ---->  /dev/sda2
> 	 dom0               domU(1)           domU(2)
>     =20
>      device is not accessible in domU(2) with an error=20
>         Buffer I/O error on device sda2, logical block 25840=20
>      Xen complains:=20
>         (XEN) grant_table.c:360:d0 Could not pin grant frame 99551

I guess it is because domU(1) tries to directly expose domU(2)'s data
pages to dom0, which it is not allowed to do.

Samuel