On Network Drivers......

On Network Drivers......

[Venu Gopal Krishna Vemula]

Hi,

  We are planning to implement a Network driver in
Linux.
Our requirement:
 A driver of layered one.., in which one layer
communicates with another. But overall there should be
only one driver . (Just like Stream's drivers, but we
don't want Stream Drivers). 
    Is there any support in Linux to implement Network
Drivers as multi layered in a single driver .If so,
please let me know where I can get good information?

With Thanks
regards,
vvgkrishna_78@yahoo.com


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Re: On Network Drivers......

[Alan Cox]

> information related to the Network driver(in which
> multiple layers has to develop internally)  in
> Internet, but i could not found any source code or
> information in Internet.

How strange. The kernel source code is definitely on the internet, and
definitely contains drivers that implement internal layering - 
nrdev, shaper, the sync cards, isdn

Re: On Network Drivers......

[Venu Gopal Krishna Vemula]

Sir,

--- Alan Cox <alan@lxorguk.ukuu.org.uk> wrote:

>>  A driver of layered one.., in which one layer
>> communicates with another. But overall there 
>> should be  only one driver . (Just like Stream's
>> drivers, but we don't want Stream Drivers). 

> 
> We have a single layer between the network stack and
> the drivers. However  nothing stops drivers from 
> implementing multiple  layers internally or
> calling back into other drivers. shaper is an
> example of a driver that  calls other drivers.
> 

 Can you please explain something about implementing
multiple layers internally in a Network Driver 
                     or
 inform me where i can find information (Source code)

         Today i have searched a lot to find any
information related to the Network driver(in which
multiple layers has to develop internally)  in
Internet, but i could not found any source code or
information in Internet.

With Thanks,
regards,
vvgkrishna_78@yahoo.com


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Re: On Network Drivers......

[Alan Cox]

>  A driver of layered one.., in which one layer
> communicates with another. But overall there should be
> only one driver . (Just like Stream's drivers, but we
> don't want Stream Drivers). 
>     Is there any support in Linux to implement Network
> Drivers as multi layered in a single driver .If so,
> please let me know where I can get good information?

We have a single layer between the network stack and the drivers. However
nothing stops drivers from implementing multiple layers internally or
calling back into other drivers. shaper is an example of a driver that
calls other drivers.

The basic attitude is layering is slow, and generally poor for the cache
behaviour. You want to do a single pass of the packet (or less if possible
when using DMA). However the interface is flexible and if a driver wants
to be layered or has reason for it - sure it can do it internally