[dpdk-dev] [RFC 5/8] pdump: add classic BPF filtering

[Stephen Hemminger]

On Tue, 8 Oct 2019 01:03:17 +0530
Jerin Jacob <jerinjacobk at gmail.com> wrote:

> On Mon, 7 Oct, 2019, 11:03 PM Stephen Hemminger, <stephen at networkplumber.org>
> wrote:
> 
> > On Mon, 7 Oct 2019 22:37:43 +0530
> > Jerin Jacob <jerinjacobk at gmail.com> wrote:
> >  
> > > On Mon, 7 Oct, 2019, 10:23 PM Stephen Hemminger, <
> > stephen at networkplumber.org>
> > > wrote:
> > >  
> > > > Simple classic BPF interpreter based off of libpcap.
> > > >
> > > > This is a copy of the BPF interpreter from libpcap which is
> > > > modified to handle mbuf meta data. The existing pcap_offline_filter
> > > > does not expose a way to match VLAN tags. Copying the BPF interpreter
> > > > also means that rte_pdump still does not have a hard dependency
> > > > on libpcap.
> > > >  
> > >
> > > Why not use DPDK's librte_bpf library? Rather implementing cBPF
> > > interpreter. Currently it supports eBPF which is super set of cBPF.if is
> > > this features very specific to cBPF, we clould simply implement cBPF  
> > using  
> > > eBPF or implement a new cBPF program type. That scheme could leverage
> > > existing JIT infrastructure also. Using JIT will improve filtering
> > > performance.
> > >  
> > > >
> > > >  
> >
> > Because pcap library generates cBPF in its string to BPF compiler.
> > Translating cBPF to eBPF is non trivial.
> >  
> 
> Then at least cBPF interpreter should move to librte_bpf. We can hook to
> JIT if required in future.

The opcodes for cBPF and eBPF are not compatiable.