sk_buff in 2.4.0

sk_buff in 2.4.0

[Sourav Sen]

Hi,
	As far as I understand, in 2.2.x networking code the protocol
header and data used to reside in a contiguous region in memory(pointed
to by the head, data, tail, end of sk_buff struct), 
ie skb->data is the starting point and skb->tail is the ending point. 

		        |		|
		        |		|
	skb->data --	|--------------	|
		     	|		|
			|		|
			|		|
			|		|
			|		|
	skb->tail --    |---------------|
			|		|

	And the device drivers used to transfer from skb->data to
skb->tail(==skb->len).

	My question is: Is the state of the art same in 2.4.0, ie. is
protocol header and data still has to reside contiguously? Or header and
data may be non-contiguous and the driver does scatter/gather.

	I am starting off in 2.4.0 , plz. help.

--
sourav
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Re: sk_buff in 2.4.0

[Sourav Sen]

In the patch by David S. Miller, copy_from_user() is still there (Line
14360 in zerocopy-2.4.0-1.diff). So which copy is reduced? Can anyone
explain kindly.

thanks
sourav

On Mon, 5 Mar 2001, Albert D. Cahalan wrote:

> > 	My question is: Is the state of the art same in 2.4.0, ie. is
> > protocol header and data still has to reside contiguously? Or header and
> > data may be non-contiguous and the driver does scatter/gather.
> > 
> > 	I am starting off in 2.4.0 , plz. help.
> 
> See the zero-copy patches by David S. Miller on ftp.kernel.org in
> his personal directory. If I remember right, the name of the
> directory is: /pub/linux/kernel/people/davem
> 
> These patches are now in Alan Cox's patch sets. (the "ac" kernels)
n> You may find Alan Cox's stuff in his personal directory ("alan") at
> the same FTP site.
>