AT send delay set to 0 in port probings

[Brent Sink]

> The patches should go on top of git master; not really sure what's

> happening to you. Can you run it under gdb and get a backtrace?

Here is what I was seeing from gdb:
Reading symbols from /usr/sbin/ModemManager...done.
(gdb) run
Starting program: /usr/sbin/ModemManager --debug
warning: Unable to find libthread_db matching inferior's thread library, thread debugging will not be available.
[New LWP 580]
ModemManager[577]: <info>  [1495597905.990684] [main.c:157] main(): ModemManager (version 1.7.0) starting in system bus...
[New LWP 581]
[New LWP 582]
ModemManager[577]: <debug> [1495597905.997456] [mm-sleep-monitor.c:245] mm_sleep_monitor_get(): create MMSleepMonitor singleton (0x1514cc0)
[New LWP 583]
ModemManager[577]: <debug> [1495597906.022886] [main.c:83] bus_acquired_cb(): Bus acquired, creating manager...
ModemManager[577]: <debug> [1495597906.027225] [mm-plugin-manager.c:1559] load_plugins(): [plugin manager] looking for plugins in '/usr/lib/ModemManager'
ModemManager[577]: <debug> [1495597906.058538] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'ZTE'
ModemManager[577]: <debug> [1495597906.085244] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Novatel'
ModemManager[577]: <debug> [1495597906.109977] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Iridium'
ModemManager[577]: <debug> [1495597906.144019] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Dell'
ModemManager[577]: <debug> [1495597906.169483] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Longcheer'
ModemManager[577]: <debug> [1495597906.195925] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'MTK'
ModemManager[577]: <debug> [1495597906.220452] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Haier'
ModemManager[577]: <debug> [1495597906.247849] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'X22X'
ModemManager[577]: <debug> [1495597906.273565] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Sierra'
ModemManager[577]: <debug> [1495597906.310957] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Huawei'
[LWP 582 exited]
ModemManager[577]: <debug> [1495597906.525223] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Cinterion'
ModemManager[577]: <debug> [1495597906.554053] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Thuraya'
ModemManager[577]: <debug> [1495597906.583189] [mm-plugin-manager.c:1584] load_plugins(): [plugin manager] loaded plugin 'Wavecom'

Thread 1 "ModemManager" received signal SIGSEGV, Segmentation fault.
0x76778810 in strchr () from /lib/libc.so.6
(gdb)

(gdb) bt
Python Exception <type 'exceptions.ImportError'> No module named gdb.frames:
#0  0x76778810 in strchr () from /lib/libc.so.6
#1  0x76acd548 in g_param_spec_pool_lookup () from /lib/libgobject-2.0.so.0
#2  0x76ac85b4 in g_object_new_valist () from /lib/libgobject-2.0.so.0
#3  0x76ac89e0 in g_object_new () from /lib/libgobject-2.0.so.0
#4  0x7427d9dc in mm_plugin_create ()
   from /usr/lib/ModemManager/libmm-plugin-ublox.so
#5  0x00042ef8 in initable_init ()
#6  0x76b55ba0 in g_initable_new_valist () from /lib/libgio-2.0.so.0
#7  0x76b55bec in g_initable_new () from /lib/libgio-2.0.so.0
#8  0x00043e70 in mm_plugin_manager_new ()
#9  0x0003f548 in initable_init ()
#10 0x76b55ba0 in g_initable_new_valist () from /lib/libgio-2.0.so.0
#11 0x76b55bec in g_initable_new () from /lib/libgio-2.0.so.0
#12 0x000402c8 in mm_base_manager_new ()
#13 0x0003d54c in bus_acquired_cb ()
#14 0x76bc05a8 in ?? () from /lib/libgio-2.0.so.0
Backtrace stopped: previous frame identical to this frame (corrupt stack?)
(gdb)


> P.S.: did you by any chance configure previously without a --prefix
> given?

I'm building this in Buildroot for an embedded system, so here is my configure command:
./configure --target=arm-buildroot-linux-gnueabihf --host=arm-buildroot-linux-gnueabihf --build=x86_64-pc-linux-gnu --prefix=/usr --exec-prefix=/usr --sysconfdir=/etc --localstatedir=/var --program-prefix="" --disable-gtk-doc --disable-gtk-doc-html --disable-doc --disable-docs --disable-documentation --with-xmlto=no --with-fop=no --disable-dependency-tracking --enable-ipv6  --disable-static --enable-shared  --with-qmi --with-mbim

To add to the weirdness, it seems when I enabled debug symbols in the buildroot build, the segmentation faults went away.  Now, when I run "ModemManager --debug" it works, but instead of a segmentation fault it just gives me a CRITICAL warning and moves on (object class 'MMPluginUblox' has no property named '\x90'\xf0').  Not sure if it's just a coincidence or if that is the reason, but it's what I'm seeing.

Whatever the reason, the good news is that the modem now shows up in ModemManager!
# mmcli -L

Found 1 modems:
        /org/freedesktop/ModemManager1/Modem/0 [u-blox] SARA-U260

There seems to be some errors (log files are attached), but it could be related to the fact that I do not have an antenna connected.  I'll connect one in the morning when I'm back in the office and see what happens.  Regardless, this patch does work for the SARA-U260, so thank you!

-brent
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