Re: pppd and AT+WMUX(Multiplex mode)

[carlsonj@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>