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Re: [Xen-devel] [PATCH] libxl: adjust point of backend name resolution

On 04/30/2013 11:12 AM, Ian Campbell wrote:
On Tue, 2013-04-30 at 16:03 +0100, Eric Shelton wrote:
Resolution of a backend name to a domid needs to happen a little earlier
in some cases.

For example, if a domU is specified as a backend for a
disk and, as previously written, libxl__device_disk_setdefault() calls
libxl__resolve_domid() last, then disk->backend_domid still equals
LIBXL_TOOLSTACK_DOMID when libxl__device_disk_set_backend() is called.
This results in libxl__device_disk_set_backend() making an incorrect
attempt to validate the target by calling stat() on a file on dom0,
resulting in ERROR_INVAL (see libxl_device.c lines 239-248), which
prevents creation of the frontend domain.

Likewise, libxl__device_nic_setdefault() previously made use of
nic->backend_domid before it was set.

Signed-off-by: Eric Shelton <eshelton@xxxxxxxxx>

Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

Cc: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>

Daniel, any comments?

Yes, the backend_domname conversion needs to happen earlier or the checks
against LIBXL_TOOLSTACK_DOMID won't work right - I actually had run into
this and was bypassing it by specifying a script, so this fix is needed.

Reviewed-by: Daniel De Graaf <dgdegra@xxxxxxxxxxxxx>

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