[2008.8] gsm muxing and GPRS: am i missing something?

Tom Yates madhatter at teaparty.net
Sat Sep 6 10:58:53 CEST 2008

On Fri, 5 Sep 2008, Timo Juhani Lindfors wrote:

> Tom Yates <madhatter at teaparty.net> writes:
>> i'd be happy to; can you point me to any resource that lets me know a
>> way of doing that?  does the muxd have a flag that tells it to hive
>> off a copy of the datastream (that'd be really handy about now)?
> The low-level way is to
> strace -o gsm0710muxd.strace -p `pidof gsm0710muxd` -s4096 -f -tt
> but you might get lucky if you just set "log_level = DEBUG" in
> frameworkd.conf

i couldn't find that latter file, but i attached an strace to gsmmuxd and 
i have the debug file.

however, i am annoyed to report that the test call rang through.  that is, 
everything is as mickey lauer recently suggested it would be:

On Fri, 5 Sep 2008, Michael 'Mickey' Lauer wrote:
[Tom had earlier written:]
>>  or should i be able to take an incoming call while the GPRS is up?
> Only, if the connection is kind of idle at this point, i.e. it might 
> work while you are pinging a host, it might not work when you are 
> wget'ting loads of data.
>>  and if so, should the GPRS suspend while i do, or should i be able to 
>> run them both simultaneously?
> GPRS will nicely suspend once you were lucky enough to accept the call. 
> It will automagically resume.

that is in fact exactly what happened.  since my link was idle, i saw the 
new call request coming through the modem in the trace (i have blanked 
out part of the calling number for privacy reasons):

1397  09:08:05.057420 read(5, "~\5\357\r\n%CPI: 1,0,1,0,1,0,\"07971226XXX\",129\r\n\337~", 2048) = 44
1397  09:08:05.061490 write(6, "\r\n%CPI: 1,0,1,0,1,0,\"07971226XXX\",129\r\n", 39) = 39
1397  09:08:05.867654 read(5, "~\1\377\343\5\7M\266~~\5\357\r\nRING\r\n\337~", 2048) = 22

and my openmoko rang.  once i'd answered the call and hung up, pppd seemed 
to autoresume without complaint (pings went through within seconds of 
hanging up).

i quite understand that there will be no good or reliable way to detect an 
incoming call when the modem is flooded with data; all i wanted was to be 
able to keep the pppd line up for (eg) tango map download-on-demand and 
periodic checking of email, without having "blackout windows" hours long 
when i can't be contacted.  i can now do that.

so, thank you, timo, for your help, and mickey, thanks for the 
clarification.  i can confirm that my phone does all that can be expected 
of it in the context of a GSM network!  timo, would you still like a copy 
of my trace file for reference (it's about 130k)?


       Tom Yates  -  http://www.teaparty.net

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