HEADS UP: zerocopy bpf commits impending

Robert Watson rwatson at FreeBSD.org
Mon Mar 17 06:46:01 PDT 2008

On Mon, 17 Mar 2008, Christian S.J. Peron wrote:

> Just wanted to give a heads up that I plan to start merging the work located 
> in the zerocopy bpf perforce branch.  We have been working on this project 
> for about a year now and feel that it is ready to come into the tree.
> I will begin to merge hopefully today [assuming nobody has any concerns] or 
> tommorow.  Zerocopy bpf will be disabled by default, and can be enabled 
> globally though the use of a sysctl variable. Once the kernel bits are in 
> and we sort out a couple minor nits in libpcap+tcpdump, we will be be 
> looking at getting our libpcap patches committed upstream.  I will post a 
> patch for people to experiment with in the meantime after the kernel commits 
> are complete.
> We do not anticipate this will have any effect on existing bpf consumers 
> like libpcap, tcpdump etc... so if something breaks, it shouldn't have and 
> we need to know about :) We were pretty careful about preserving the ABI. 
> The only exception to this is, netstat will need a recompile because the 
> size of it's bpf stats structure changed.
> So if there are any objections or concerns, now is the time to raise them.

Per previous posts, interested parties can find the slides on the design from 
the BSDCan 2008 developer summit here:


Robert N M Watson
Computer Laboratory
University of Cambridge

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