Re: [PATCH v2] libxl: Introduce a template for devices with a controller

[Wei Liu <wei.liu2@citrix.com>]

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.