[Click] Uniform handler interface?

[Eddie Kohler]

Roman,

Roman Chertov wrote:
> Can you actually open a socket in a kernel module?  My impression was 
> that it would be hard to do as there is no easy to use API (that I could 
> find) to deal with file descriptors (e.g. no straight forward way to 
> open files on disk).  Surely, there is rich Linux API, but most of the 
> calls are for user-kernel communication.

That is correct, it would be hard to do.  But it would be *possible* :)

I think in the end doing so would be silly, since KernelHandlerProxy works 
just fine.

Eddie


> 
> Just curious to hear more on this subject.
> 
> Roman
> 
> Eddie Kohler wrote:
>> Björn,
>>
>> A ControlSocket for kernel space might be interesting, but it is not 
>> top on our list of priorities.
>>
>> There are ways to translate from ControlSocket to kernel handlers, 
>> however. For instance, you can run a user-level Click proxy that 
>> translates ControlSocket requests to kernel handlers.
>>
>> man KernelHandlerProxy
>> man ControlSocket   -- look for the PROXY keyword argument
>>
>> Eddie
>>
>>
>>
>>
>> Björn Smedman wrote:
>>> Hi,
>>>
>>> We have some click router configurations that I am trying to move from
>>> kernel-space to user-space. Making the switch was as simple as 
>>> changing the
>>> command we use to load the configuration from "click-install" to 
>>> "click". We
>>> where very impressed to find this complex router config with custom 
>>> elements
>>> and all working exactly as before without a single change to either 
>>> config
>>> or code. :)
>>>
>>> But the handler interface differences seem to require manual work. We 
>>> have a
>>> control process that interacts with the click router through handlers 
>>> (both
>>> read and write), and the interface to these handlers has changed 
>>> completely
>>> after the move to user-space. In kernel-space we used the clickfs 
>>> handler to
>>> file mappings. In user-space it seems we have to use ControlSocket.
>>>
>>> Is it possible to use ControlSocket in kernel-space as well? Is there 
>>> some
>>> "best practice" for interacting with router configs that can be moved 
>>> freely
>>> between user- and kernel-space? It seems to me that this is such a
>>> compelling feature (to be able to debug in user-space and then move to
>>> kernel for better performance) that it would be worth while to 
>>> abstract the
>>> handler interface.
>>>
>>> Thank you in advance.
>>>
>>> Best regards,
>>>
>>> Björn
>>
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>