From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wei Liu <wei.liu2@citrix.com>
Subject: Re: [PATCH v2] libxl: Introduce a template for devices
 with a controller
Date: Tue, 1 Dec 2015 15:58:55 +0000
Message-ID: <20151201155855.GX21588@citrix.com>
References: <1448971798-3498-1-git-send-email-george.dunlap@eu.citrix.com>
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To: George Dunlap <george.dunlap@eu.citrix.com>
Cc: Juergen Gross <jgross@suse.com>, Olaf Hering <olaf@aepfle.de>, Wei Liu <wei.liu2@citrix.com>, Ian Campbell <ian.campbell@citrix.com>, George Dunlap <george.dunlap@citrix.com>, xen-devel@lists.xen.org, Ian Jackson <ian.jackson@citrix.com>, Chun Yan Liu <cyliu@suse.com>
List-Id: xen-devel@lists.xenproject.org

On Tue, Dec 01, 2015 at 12:09:58PM +0000, George Dunlap wrote:
[...]
> diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
> index 6b73848..44e2951 100644
> --- a/tools/libxl/libxl.h
> +++ b/tools/libxl/libxl.h
> @@ -1396,6 +1396,71 @@ void libxl_vtpminfo_list_free(libxl_vtpminfo *, int nr_vtpms);
>   *
>   *   This function does not interact with the guest and therefore
>   *   cannot block on the guest.
> + *
> + * Controllers
> + * -----------
> + *
> + * Most devices are treated individually.  Some classes of device,
> + * however, like USB or SCSI, inherently have the need to have a
> + * hierarchy of different levels, with lower-level devices "attached"
> + * to higher-level ones.  USB for instance has "controllers" at the
> + * top, which have buses, on which are devices, which consist of
> + * multiple interfaces.  SCSI has "hosts" at the top, then buses,
> + * targets, and LUNs.
> + *
> + * In that case, for each <class>, there will be a set of functions
> + * and types for each <level>.  For example, for <class>=usb, there
> + * may be <levels> ctrl (controller) and dev (device), with ctrl being
> + * level 0.
> + *
> + * libxl_device_<class><level0>_<function> will act more or

Missed "level0" comment from Chunyan?

> + * less like top-level non-bus devices: they will either create or
> + * accept a libxl_devid which will be unique within the
> + * <class><level0> libxl_devid namespace.
> + *

Ditto.