about userlevel and kernel level

[Douglas S. J. De Couto]

you should probably use userlevel unless there is some good reason not 
to.  it will make your life easier....

i have implemented a wireless routing system in click, see the 
clickdir/conf/grid.click configuration to get some ideas on how to work 
at userlevel.

d


testclick wrote:
> Hi, Eddie,
> 
> thanks for your reply.I still have some questions/ I
> still confuse a bit.
> 
> I am using kernel level, I do feel it is hard to
> debug. Is there any other way to debug except
> click_chatter the information.I actually use this
> function to trace the program step sometimes.
> 
> Then I am wondering whether it is necessary for me to
> use kernel level. My work is to implement a wireless
> network and the routers will do different action
> arroding to their roles in the network. My design is
> that each router will have a corresponding
> click-router config which will lead the router/PC to
> do the exact router work. and I should build some
> elements for the extra functions of the different
> roles.
> 
> fianlly is how can I trace the packets sent to the
> correponding device eth? 
> 
> --- Eddie Kohler <kohler at icir.org> wrote:
> 
>>>Maybe this is quite simple, but would any of you
>>>kindly tell me the difference between userlevel
>>
>>and
>>
>>>kernel level. In the userlevel, can I build extra
>>>elements? How do you choose to use user level and
>>>kernel level?
>>
>>The two drivers are different in that they run at
>>different places -- at
>>user level or in the kernel. These environments
>>impose different
>>constraints and support different functionality. For
>>example, you can't
>>implement device polling at user level, but you
>>can't link with C++
>>standard libraries or make system calls in the
>>kernel. Also, user level is
>>easier to debug. There are elements that build only
>>at user level, and
>>elements that build only for the kernel, but most
>>elements compile
>>perfectly well for either.
>>
>>Eddie
> 
> 
> 
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-- 
Douglas S. J. De Couto    decouto at lcs.mit.edu