Re: pppd and AT+WMUX(Multiplex mode)

["Simon Chow" <simonchow@keytechsys.com.hk>]

<carlsonj@workingcode.com> wrote in message
news:16638.36676.350168.813237@carlson.workingcode.com...
> Simon Chow writes:
> > I am researching how to handle the AT packets and Data packets offered
by
> > the Wavecom GSM modem in AT+WMUX=1 mode. I want to modify the pppd
programme
> > and I think that the tty.c in pppd may be the key to change. The
charshunt
> > function manipulates both the raw bytes sent from and received by the
serial
> > port. However, I am still in an initial stage.
>
> I don't think that analysis is right.  The charshunt task is invoked
> only in a few cases (e.g., where the 'record', 'notty', or 'socket'
> options are used), and isn't the normal data path.  The normal data
> path is in the kernel, not user space.
>
> > I wonder if the pppd tool can handle the multiplex mode offered by
Wavecom
> > GSM modem. Thanks.
>
> Not today.  I think you'd have to modify the PPP modules in the Linux
> kernel to detect the switching mechanism and feed the data up to pppd
> first.  Otherwise, it'll probably be handled as bad PPP frames and
> discarded.
>
> -- 
> James Carlson                                 <carlsonj@workingcode.com>
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How about I modify the ppp_async_input function in ppp_async.c to detect the
0xAA and 0xDD, and the ppp_async_push function to encapsulate the PPP frame
with 0xDD?