Failed to mount usb stick on android emulator

Issue

I have an android device with usb ports. I'm trying to do an android application that stores a file to a usb stick. First, I need to validate it on an emulator before I can deploy it in the device. My problem is that the emulator doesn't mount well the usb stick. So far, I can detect the usb connection (in app and with lsusb) but I cannot find the path to save my file as the usb stick seems not to be mounted. To reproduce:

connect usb to pc:

$ lsusb
Bus 001 Device 016: ID ffff:5678

Create dev rules for this specific usb in /etc/udev/rules.d/99-usb-android.rules:

SUBSYSTEM=="usb", ATTRS{idVendor}=="ffff", ATTRS{idProduct}=="5678", MODE="0666"
SUBSYSTEM=="usb_device", ATTRS{idVendor}=="ffff", ATTRS{idProduct}=="5678", MODE="0666"

Reload udev rules:

 sudo udevadm control --reload-rules

Run the emulator with usb support:

emulator -avd x86-machine -qemu -usb -device usb-host,vendorid=0xffff,productid=0x5678

Once it starts I see some repeating errors on the dmesg

[   36.300218] usb 1-1: reset full-speed USB device number 2 using uhci_hcd
[   37.240093] usb 1-1: reset full-speed USB device number 2 using uhci_hcd
[   38.180262] usb 1-1: reset full-speed USB device number 2 using uhci_hcd
[   38.652826] sd 2:0:0:0: [sda] Unaligned partial completion (resid=4095, sector_sz=512)
[   38.659008] sd 2:0:0:0: [sda] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK
[   38.664371] sd 2:0:0:0: [sda] tag#0 CDB: Read(10) 28 00 00 00 00 00 00 00 08 00
[   38.668527] print_req_error: I/O error, dev sda, sector 0
[   38.671306] Buffer I/O error on dev sda, logical block 0, async page read
[   38.674756] Dev sda: unable to read RDB block 0
[   39.100212] usb 1-1: reset full-speed USB device number 2 using uhci_hcd
[   40.040269] usb 1-1: reset full-speed USB device number 2 using uhci_hcd

However, I can see the usb if I connect to the shell

$ adb root
$ adb shell
emulator:# lsusb
Bus 001 Device 001: ID 1d6b:0001
Bus 001 Device 002: ID ffff:5678

and I have an app which recognizes when an usb key is connected and shows a message with its info. I have read in some questions that the usb stick is mounted in /mnt/media_rw/[HEX-NUM] but I have nothing in that folder

emulator:/mnt/media_rw # ls
emulator:/mnt/media_rw # 

Is the usb stick being really mounted? if not, how can I do it? thanks

Solution

I ran the emulator this way and it works now

./emulator @AVD_NAME -no-snapshot -qemu -device usb-ehci,id=ehci -device usb-host,bus=ehci.0,vendorid=0xffff,productid=0x5678

Answered By - afvmil