MC7455 Kernel Crash SMSTools3 APU Board

IoT Modules MC/EM Series
1

Hello together,

we are using a APU Board with the MC7455 modem and smstools 3 to sent sms with them.
Used Kernel is 4.9.0-bpo.
We are only using at commands to communicate with the modem.
At some point the modem will be resetted and reconnected to the system via udev rules and at commands.
Are there any known bugs with this hardware combination which could lead to a kernel crash?

Best Regards,
AM

2

Are you using Gobiserial driver?
You can write a script to replace the sms tool. This can isolate if the sms tool makes the reset.

3

Gobiserial drivers are not used.
This worked before on the same mainboard ,modem and the same software.
If I switch back to a older mainboard within the same series there is no issue.
Since this is a really strange behaviour we switched all the hardware components.
Without smstools running there is also no kernel crash, or at least I did not had one after a day.
I will write a script which resets the modem without smstools involved and test it for some time.

4

then it seems smstools is the problem.

5

But it is not an issue with the same board but older. (Same software/modem)
APU from 2 months ago does not have an issue.

6

you can use AT command on microcom tool or AT command port and see if there is crash.

7

I have disabled smstools and have sent at commands (AT+CFUN=1,1) to the modem.
At some point it crashed again.
Also I have set all running crons to *****, after a wihile crashed again.
Without attached modem no issues with crons set to every minute.

8

Do you have the AT log?
Can you attach the linux script?
Are you using the latest fw?

9

No I do not have an excact log, but what happens is only this:
AT+CFUN=1,1
OK
AT+CFUN=1,1
OK
…
And so on.

The script:

#!/bin/bash
exisits=$(cat /var/run/sendcommands.pid)

if [ -z "$exisits" ]; then

    if [ -L '/dev/gsm0' ]; then
        echo -e -n 'AT+CFUN=1,1\015' > /dev/gsm0
    else
        udevadm control --reload-rules && udevadm trigger
    fi
    sleep 20
	
    rm -f /var/run/sendcommands.pid
fi

The firmware of the modem: 02.33.03.00 which is the latest generic.

Best Regards,
A.M.

10

not quite sure what you mean, AT+CFUN=1,1 is just to reset the module

11

Yes, this command just resets the modem, which should not result in a kernel crash at all.
But after some resets the system runs into errors and the kernel will crash at some point, which should not happen.
I am talking about 100-200 times the reset command.
I will test this with a installed pfsense.
A system not communicating with the modem does not have issues.