On Wed, Nov 24, 2010 at 01:59:47PM +1300, Andrew Thompson wrote:
> On 24 November 2010 13:36, Jung-uk Kim <j...@freebsd.org> wrote:
> > On Tuesday 23 November 2010 07:18 pm, Weongyo Jeong wrote:
> >>    - BPF was normally for ethernet frames (most operations were
> >> based on mbuf including the machine filter and there were a lot of
> >> assumptions the input buffer is mbuf type.  For example, handling
> >> BPF_LD|BPF_W|BPF_ABS).  However the USB packet isn't like mbuf
> >> style that it's just a linear buffer.  So the most important code
> >> or assumption wasn't compatible.
> >
> > BPF can deal with linear buffer just fine.  For example, ng_bpf(4)
> > does it.  Please see sys/netgraph/ng_bpf.c.
> >
> >>    - Just making the patch for BPF code, it looked like a trick or
> >> a hack to me because I couldn't define what BPF should be.
> >
> > If you don't want to touch bpf.c for some reason, netgraph(4) (->
> > ng_bpf) may be an alternate solution for you.
> >
> >>    - I could not define BPF exactly myself that what BPF should
> >> cover. I agreed with that BPF is for ethernet packet filtering but
> >> could not make sure myself that BPF could cover USB packets.
> >
> > BPF is a generic packet filter machine, i.e., bytecode is generic
> > enough for any type of data stream.
> I agree that this is the best way forward, if it can be achieved.

Attached is what I really wanted to do.  USB pf is greatly simplified
and perfectly satisfy me.  It'll fully benefit from changes of BPF code.

I'll commit this version into HEAD if no objections.

Weongyo Jeong

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