A JIT for packet filters [LWN.net]

A JIT for packet filters

Posted Apr 14, 2011 16:28 UTC (Thu) by wahern (subscriber, #37304)
In reply to: A JIT for packet filters by trasz
Parent article: A JIT for packet filters

Links? I can't find any JIT compiler in the FreeBSD kernel, at least skimming code in sys/net/bpf.c or bpf_filter.c.

I'd be interested in this because I'm looking for a tiny JIT compiler. MyJIT is the best I can find so far, but it can't recover from OOM errors and it's quite large, which means I'm too lazy to fix it.

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A JIT for packet filters

Posted Apr 14, 2011 16:37 UTC (Thu) by trasz (guest, #45786) [Link]

See http://fxr.watson.org/fxr/source/net/bpf_jitter.c and http://fxr.watson.org/fxr/source/amd64/amd64/bpf_jit_mach....

It was introduced six years ago, with this commit:

r153151 | jkim | 2005-12-06 03:58:12 +0100 (Tue, 06 Dec 2005) | 17 lines

Add experimental BPF Just-In-Time compiler for amd64 and i386.

Use the following kernel configuration option to enable:

options BPF_JITTER

If you want to use bpf_filter() instead (e. g., debugging), do:

sysctl net.bpf.jitter.enable=0

to turn it off.

Currently BIOCSETWF and bpf_mtap2() are unsupported, and bpf_mtap() is
partially supported because 1) no need, 2) avoid expensive m_copydata(9).

Obtained from: WinPcap 3.1 (for i386)