[RFC] USBdump patches

[Weongyo Jeong]

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.
   - 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.
   - 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.

Please tell me your opinion if you guys have better approach.

regards,
Weongyo Jeong