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Subject: Re: On Network Drivers......
To: vvgkrishna_78@yahoo.com (Venu Gopal Krishna Vemula)
Date: Mon, 20 Aug 2001 13:36:58 +0100 (BST)
Cc: linux-kernel@vger.kernel.org
In-Reply-To: <no.id> from "Venu Gopal Krishna Vemula" at Aug 20, 2001 05:14:09 AM
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From: Alan Cox <alan@lxorguk.ukuu.org.uk>
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>  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