Sachin Gole
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4G Modem interface in Linux Guest OS
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Sachin Gole
01/04/2023 8:04 AM
post122100
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4G Modem interface in Linux Guest OS
Hello All,
4G Simcom A7672S modem is connected through USB on R-Car H3e. Inside QNX hypervisor host with devc-serusb driver, we are
able to run pp0 interface and it gives ip from sim service provider. Internet is working.
Next, same we want to get inside Linux Guest VM,
1) Created a vdev as follows,
vdev virtio-console
sched 7
loc 0x5b130000
intr gic:303
hostdev /dev/serusb1
2) On linux guest we can see the device as hvc0. The path is /dev/hvc0. Logs shows incoming calls.
For ppp interface connect script is failing every time. Logs shows that AT command is not sent to modem as per below
error log,
root@root:~# pppd
[ 28.961403] PPP generic driver version 2.4.2
Connect script failed
root@root:~# plog
Jan 2 00:49:23 root chat[540]: abort on (ERROR)
Jan 2 00:49:23 root chat[540]: abort on (+CGATT: 0)
Jan 2 00:49:23 root chat[540]: send (AT^M)
Jan 2 00:49:23 root chat[540]: timeout set to 12 seconds
Jan 2 00:49:23 root chat[540]: expect (OK)
Jan 2 00:49:35 root chat[540]: alarm
Jan 2 00:49:35 root chat[540]: Failed
Jan 2 00:49:35 root pppd[533]: Connect script failed
Jan 2 00:49:35 root pppd[533]: Exit.
Our conclusion is that the AT command is not getting passed from guest to the modem device connected on host.
Question :
Approach taking dev-serusb1 to guest os via vdev console is correct way? Or there is another approach.
hvc0 in the dev is write protected or something need to be changed over there?
We are also getting the device as /dev/vport0p0. But we are unable to use the device & what is the functionality of
same. If we try to cat the vport0p0 then it says No such device or addresses
Thanks in Advance
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