linux 2.4

[John Jannotti]

I think this is in support of the zero-copy interface.  LWN talks a bit
about the new interface:

 To handle all of this stuff, the zero-copy networking patch makes some
 fundamental changes to the networking core code. Traditionally, packets
 are passed around via a struct sk_buff structure, usually referred to as
 an "skb." The skb contains the entire packet, headers and all. With
 zero-copy, an skb can now be "paged," or "nonlinear," meaning that it
 consists of several pieces which are not contiguous in memory. Much of the
 code which handles skb structures must be changed to take this new
 structure into account.

 (more at http://lwn.net/2001/0419/kernel.php3)

My reading is that there is now a way a way for user code to provide
scatter-gather type requests that will go to drivers with zero-copy, so
transmit drivers must be able to handle fragmented packets.  I don't think
Click will ever *receive* such packets from the network driver, but I don't
know for sure.

  jj