Re: [Xen-devel] [PATCH 20 of 29 RFC] libxl: introduce libxl hotplug public API functions

[Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>]

Roger Pau Monne writes ("[Xen-devel] [PATCH 20 of 29 RFC] libxl: introduce 
libxl hotplug public API functions"):
> libxl: introduce libxl hotplug public API functions
> 
> These functions mimic the name used by the local device functions,
> following the nomenclature:

I think these should be private functions.  Your new device daemon is,
I think, part of the implementation of libxl, not something that
another toolstack on top of libxl will reasonably want to replace.

This is a new departure for libxl, which doesn't currently have any
internal executables.

> The xenstore structure used by vbd disk entries:
> 
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/pdev_path
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/vdev
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/script
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/removable
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/readwrite
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/is_cdrom
> /hotplug/<backend_domid>/<frontend_domid>/vbd/<devid>/state
> 
> and vif devices use the following:
> 
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/mtu
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/model
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/mac
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/ip
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/bridge
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/ifname
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/script
> /hotplug/<backend_domid>/<frontend_domid>/vif/<devid>/nictype
> 
> This will allow us to pass the libxl_device_disk and libxl_device_nic
> struct from Dom0 to driver domain, and execute the necessary backends
> there.

Is this really the best encoding of this information in xenstore ?

If we're allowed to assume that the backendd is a libxl program too,
and of a reasonably similar version, perhaps we should have some kind
of idl-generated mapping from xenstore keys to struct members ?

Ian.

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