Re: [PATCH 4/4] libxl: add support for vscsi

[Ian Campbell <ian.campbell@citrix.com>]

On Mon, 2015-03-02 at 15:20 +0100, Olaf Hering wrote:
> On Mon, Mar 02, Olaf Hering wrote:
> 
> > +++ b/tools/libxl/libxl_types.idl
> 
> > +libxl_vscsi_hctl = Struct("vscsi_hctl", [
> > +    ("hst", uint32),
> > +    ("chn", uint32),
> > +    ("tgt", uint32),
> > +    ("lun", uint32),
> > +    ])
> > +
> > +libxl_vscsi_dev = Struct("vscsi_dev", [
> > +    ("vscsi_dev_id",     libxl_devid),
> > +    ("remove",           bool),
> > +    ("p_devname",        string),
> > +    ("pdev",             libxl_vscsi_hctl),
> > +    ("vdev",             libxl_vscsi_hctl),
> > +    ])
> > +
> > +libxl_device_vscsi = Struct("device_vscsi", [
> > +    ("backend_domid",    libxl_domid),
> > +    ("devid",            libxl_devid),
> > +    ("v_hst",            uint32),
> > +    ("vscsi_devs",       Array(libxl_vscsi_dev, "num_vscsi_devs")),
> > +    ("feature_host",     bool),
> > +    ])
> 
> IanC, you made a comment about "vscsi_dev_id" in the pastebin.com
> comment about libxl_vscsi_hctl:
> '- devid is just "devid" in all other places, not "TYPE_dev_id".'

> Its used as <domid>/<vhost>/vscsi-devs/dev-<vscsi_dev_id>/.  What name
> should be used to reference the devices? Also just "devid" even if it
> refers to devices "private" to the vscsi host?

Not sure. PCI uses vdevfn, which by extension would be vdevid here
(assuming I've understood what you are suggesting correctly and
therefore the analogy is valid).

Or could it be the case that there is no need to expose this value to
the user in the first place and libxl could just make up the index
numbers internally? Why would they want to configure it or retrieve it?

Is it actually the same as the offset into the vscsi_devs array?

How is it intended to be different from the vdev field?

Ian.