USB Mass Storage can't be detected as /dev/sdb

Hello,

I followed the following instructions: (switch 2 is on the low position)

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

For flashing kernel and rootfs, the eMMC space needs to be mounted, we will use uboot ums command for that.

Checking the emmc device...In most cases the emmc device will be sdb unless you have multiple mass storage device connected to your PC.

-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------

After typing  ums 0 mmc 0, I can see one USB device (Netchip usb download gadget) is detected in VM Ubuntu 14.04.  Dmesg gives the following messages:

...

[  997.389492] usb 1-1: new high-speed USB device number 2 using ehci-pci

[  997.649479] usb 1-1: New USB device found, idVendor=0525, idProduct=a4a5

[  997.649489] usb 1-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3

[  997.649492] usb 1-1: Product: USB download gadget

[  997.649493] usb 1-1: Manufacturer: FSL

[  997.712231] usb-storage 1-1:1.0: USB Mass Storage device detected

[  997.717282] usb-storage 1-1:1.0: Quirks match for vid 0525 pid a4a5: 10000

[  997.717444] scsi host33: usb-storage 1-1:1.0

[  997.725268] usbcore: registered new interface driver usb-storage

[  997.740037] usbcore: registered new interface driver uas

[ 1020.196637] usb 1-1: reset high-speed USB device number 2 using ehci-pci

[ 4042.905267] hrtimer: interrupt took 11121686 ns

....

it is clear that the usb download gadget is found, but  fdisk -l doesn't show the /dev/sdb

$ sudo fdisk -l

Disk /dev/sda: 536.9 GB, 536870912000 bytes

255 heads, 63 sectors/track, 65270 cylinders, total 1048576000 sectors

Units = sectors of 1 * 512 = 512 bytes

Sector size (logical/physical): 512 bytes / 512 bytes

I/O size (minimum/optimal): 512 bytes / 512 bytes

Disk identifier: 0x000928fe

Device Boot      Start         End      Blocks   Id  System

/dev/sda1   *        2048  1031798783   515898368   83  Linux

/dev/sda2      1031800830  1048573951     8386561    5  Extended

/dev/sda5      1031800832  1048573951     8386560   82  Linux swap / Solaris

Would you please tell me how can I get the usb download gadget detected as /dev/sdb ?

In Google unfortunately I can't find any solution. Any hint will be appreciated.

Thanks

Elem