about userlevel and kernel level

[testclick]

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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