Re: [Xen-devel] Is there example code and/or documentation for developing a Xen back-end/front-end driver pair?

[Randy Thelen <rthelen@xxxxxxxxxx>]

Ewan Mellor wrote:

> Attached are some notes of mine.  They are quite old, but I think  
> it all is
> pretty much relevant.
>
> Basically, a backend watches /local/domain/0/backend/<deviceClass>  
> and a
> frontend watches /local/domain/<domID>/device/<deviceClass>.  When  
> the tools
> write into those directories in the store, the drivers get a watch  
> fired, and
> check those directories to see the new device details.  The new  
> internal state
> is created based on that.
>
> If you are using the normal Xenbus code, then you can register your  
> device
> driver with the Xenbus layer, and much of this is done for you.
>
> The drivers themselves use a simple state machine to handshake  
> between front
> and backends.
>
> The backends use hotplug / udev events inside domain 0 to trigger  
> scripts for
> simple bringup/teardown stuff, like attaching new vifs to bridges or
> whatever.  The tools watch for a specific node to be written in the  
> store to
> indicate that this hotplug phase has succeeded (it's usually the  
> one that does
> the final sanity checking and often has to bail out).
>
> HTH,
IHI {It Helps Indeed!}  Thanks.  Could I encourage you to post those  
on the XenSource Wiki?
-- Randy


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