On Tue, Nov 23, 2010 at 07:36:47PM -0500, Jung-uk Kim wrote:
> On Tuesday 23 November 2010 07:18 pm, Weongyo Jeong wrote:
> > On Tue, Nov 23, 2010 at 06:52:36PM -0500, Jung-uk Kim wrote:
> > > On Tuesday 23 November 2010 06:31 pm, Jung-uk Kim wrote:
> > > > [CC sanitized]
> > > >
> > > > On Tuesday 23 November 2010 06:01 pm, Hans Petter Selasky wrote:
> > > > > Dear Weongyo,
> > > > >
> > > > > > NACK. You already could recognize that the patch is quite
> > > > > > big and multiple patches are mixed into one. Please
> > > > > > separate into smallest pieces then send freebsd-usb@ again.
> > > > > > I don't want to do a jumbo jump.
> > >
> > > Technically, I don't like the copy-and-pasted code from bpf.c and
> > > bpf_filter.c. Was it really necessary? Is the dump file in PCAP
> > > format?
> > >
> > > Please enlighten me if I missed something.
> > The following paragraph is extracted from email I sent to rwatson@
> > because he also asked same question to me. And I added CC to
> > freebsd-usb@ to share my story with other developers who might
> > think similar.
> > Hello Roberts,
> > I understand what you're worry and agree with you that if I could
> > remove this duplication it'd be best one. I think it could be
> > happen enough later if we could reach the consensus.
> > The biggest confusions I encountered during implementing?
> > (porting) it for USB packet filter were as follows. Please let me
> > know if there are something I missed:
> > - 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.
Oh I see what you mean. `buflen' was a key variable whether the buffer
is mbuf or linear buffer that I missed it. You saved my enough time.
I think we could reduce significant code of USB pf. And I'll provide a
second patch for this. Please forgive my ignorance. Thank you!
firstname.lastname@example.org mailing list
To unsubscribe, send any mail to "freebsd-usb-unsubscr...@freebsd.org"