From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wei Liu <liuw@liuw.name>
Subject: Re: Block front and back connection
Date: Tue, 9 Aug 2011 10:27:55 +0800
Message-ID: <20110809022755.GA1783@limbo>
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To: Daniel Castro <evil.dani@gmail.com>
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On Mon, Aug 08, 2011 at 11:17:52PM +0900, Daniel Castro wrote:
> Hello,
> 
> I am trying to make my frontend block driver connect to xen block
> backend. I have the ring and gref, yet I do not know where in xenstore
> should I write the keys to tell the backend to connect to my frontend.
> 

You can find some clues in libxl_devices.c .

The frontend path is

/local/domain/FRONTEND_DOMID/device/DEVICE_KIND/DEVID

The backend path is

/local/domain/BACKEND_DOMID/backend/BACKEND_KIND/FRONTEND_DOMID/DEVID

Often the BACKEND_DOMID is 0.

And looking into Linux kernel's xen-{blkfront,blkback} helps you a
lot.

Then you can switch xenbus state after proper values are in place, so
that frontend and backend can connect to each other.

Wei.