Can not detect the serial port number when Connect to the nordic 51822 using jlink in ubuntu 14.4

Question

As shown in title, I am using the ubuntu 14.04 in virtualbox.
When I connect the Nordic 51822 development kit to my PC, I can only detect the serial number of this device, and I can not find the serial port number using 'dmesg | grep xx' like ( devzone.nordicsemi.com/.../) 
 In expectation, I would get the following mesg: 
 kaspar@ubuntu:~/RIOT$ dmesg | grep 'cdc_acm.*USB ACM device' | tail
[25398.308837] cdc_acm 1-1:1.0: ttyACM0: USB ACM device
[26152.729879] cdc_acm 1-1:1.0: ttyACM0: USB ACM device
 
 However, I only get following mesg without the filter of grep: 
 [ 785.440538] usb 1-2: new full-speed USB device number 3 using ohci-pci
[ 785.641516] usb 1-2: New USB device found, idVendor=1366, idProduct=0101
[ 785.641519] usb 1-2: New USB device strings: Mfr=1, Product=2, SerialNumber=3
[ 785.641520] usb 1-2: Product: J-Link
[ 785.641521] usb 1-2: Manufacturer: SEGGER
[ 785.641522] usb 1-2: SerialNumber: 000000123456
 
 So, how to fix this problem? without the serial port I can not just flash the hello-world example! 
 serial.serialutil.SerialException: could not open port 000000123456: [Errno 2] No such file or directory: '000000123456'

Stian Røed Hafskjold · Accepted Answer

What kind of development kit do you have? Is it the PCA10028? I see that dmesg reports idProduct=0101 , this is the JLink without USB CDC. If you have the PCA10028, you can try to re-program the JLink interface firmware, found here: www.nordicsemi.com/.../52276 . Hold down the reset button while turning on, dmesg should now show New USB device found, idVendor=0d28, idProduct=0204 . Then copy the JLink FW file over to the JLink mass storage device. Power cycle the kit and dmesg should now show New USB device found, idVendor=1366, idProduct=1015 
 If you don't have the PCA10028 and using a regular JLink to flash, there might not be any serial interface you can use. However, you don't really need the serial interface to flash things to the chip. You can use JLinkExe like this: 
 device nrf51
connect
 > interface: SWD
 > speed: default
loadfile your_file.hex
 
 (or just the nrfjprog )