Re: DomU-Dom0 communication question

[mk.xen-devel@simplecheck.net]

On 5/2/07, Ryan Riley <rileyrd@gmail.com> wrote:
> > I am looking at backend/frontend drivers and I don't think it would work
> for what I want to do as fron/back ends don't have any devices associated
> with it.
> > 
> 
> Hmm, it sounds like you may be a bit confused regarding how the split
> drivers work.  

Yes, I am :-)

> For any useful frontend/backend device each side ends up
> being two drivers in one.  One is the frontend/backend driver, the other is
> the device that the OS sees.  For example, the networking frontend has all
> of the code the being a Xen frontend driver (event channels, probe handling,
> etc) and is also a network device that the guest interacts with.  In a sense
> it registers itself as two drivers. 

That is the driver I was going through to get an idea how it works. I see the network adapter registration part, but since I am not familiar with network drivers APIs I got confused what exactly is going on. 

> You could definitely write a split driver that has character devices on both
> ends that share data.  My backend driver for the project I mentioned above
> is exactly that.  (Frontend kernel puts data onto a ring buffer, backend
> kernel reads it off and makes it available as a character device.) 

Sounds exactly what I need, except I was thinking to have messages in both directions.

> This probably sounds bad, but if you can get away with it I would do
> everything is user space and send your arbitrary data/buffers over the
> network link.  Trust me when I say that you'll lose less hair that way. 

I think, the split drivers give me a better control for the task I am doing. I do not want to rely on network being setup correctly.

> If you decide to go the split driver route, I can supply you with my code. 
> It isn't pretty, but it may help you out.  Let me know if you're interested.

I am definitely  interested! I was out of writing Linux drivers for quite some time and I appreciate any help I can get.

Thanks.

Max