Re: BSDi BPF extension

[itojun () iijlab net]

--------


>       (sorry i lost the original posting)
>
>       BSDi BPF extension is part of BSDi packet filter ("ipfw", don't confuse
>       it with FreeBSD one with the same name).  i've contacted BSDi guy if
>       they could release the code to the public, so please hold for a moment
>       on the official answer.  time have passed since he gave me an OK to
>       release BSDi BPF, his management have changed (WindRiver chewed up
>       BSDi and stuff), so we need a positive response from him before making
>       any action.
>
>       BSDi BPF extension has a few good things and a few bad things:
>       good things:
>               it can do "protochain" in one BPF insn.  backward jump is
>               prohibited in kernel BPF interpreter to avoid infinite loop,
>               so BSDi BPF has a BPF insn to do "protochain" operation.
>
>               it has 128bit registers, which would help IPv6 parsing.
>
>       bad things:
>               BSDi BPF changed interpretation of some additional BPF insn
>               (and new interpretation like 128bit register) without having
>               any version identification.  there's no way to identify
>               what version of BPF engine is installed in the kernel, so we
>               can't make libpcap compiler to work on pre-BSDi and BSDi BPF
>               engine.
>
>       the "bad things" part really bothers me, as if we switch to BSDi BPF,
>       we require every operating system to switch their kernel BPF evaluation
>       engine to BSDi one.  it is not a smooth transition, there needs to be
>       a big "flag day".
>
> itojun
> -
> This is the TCPDUMP workers list. It is archived at
> http://www.tcpdump.org/lists/workers/index.html
> To unsubscribe use mailto:tcpdump-workers-request () tcpdump org?body=unsubscribe
-
This is the TCPDUMP workers list. It is archived at
http://www.tcpdump.org/lists/workers/index.html
To unsubscribe use mailto:tcpdump-workers-request () tcpdump org?body=unsubscribe