How do I connect two VMs via virtual USB?

[jcejohnson]

On a Windows 10 host I have an Android x86 VM and a CentOS 7 VM. I have Android Studio installed in the CentOS VM and would like to deploy an app to the Android x86 VM. With a real Android device I would do this via USB. So, what I would like to do is connect the two VMs via virtual USB so that I can deploy to & debug on the virtual Android device.

FWIW, I'm using the Android x86 VM because the Android emulator in the CentOS VM is too slow to be useful.

[michaln]

Not possible. USB was not designed for connecting two hosts.

[jcejohnson]

Fair enough. But the port on the Android device isn't a device port, not a host port. I guess the answer, then, is that virtualbox doesn't emulate device ports?

[socratis]

But the port on the Android device isn't a device port, not a host port.

I'm not quite sure I understand the above statement. Could you clarify?

Since there are no Guest Additions (GAs) for Android (heck Android is not even a supported guest), you cannot use shared folders. And as Michal pointed out, there's no shared USB.

You can either use an FTP client from Android (is there one?) to log to an FTP server on your host and transfer your files like that, or use a "common" 3rd storage device where you store your app from your host, and access it from your guest. That means that at a minimum, you have to mount the common vdi, copy your app, shut down the CentOS VM, launch the Android VM, copy the app, rinse and repeat. I believe the former is more straightforward.

[jcejohnson]

Clarity:

On a physical Android device, the USB port is a device port (the same as a thumb drive, camera, etc.) whereas on a computer the USB port is a host port. A host port initiates communication, a device port responds. Somebody else can explain that better than I: http://electronics.stackexchange.com/qu ... and-device

When an Android device is plugged into a computer where adb (android debug bridge) is installed, adb will establish a connection to the device and can then copy files, deploy applications, etc. During development, that link can be used to debug running apps. My hope was that a virtualbox-hosted Android x86 instance would be able to present a USB device port (the same as physical hardware does) such that the virtualbox host or, ideally, another guest would be able to connect to it via adb.

Shared folders, ftp, etc. doesn't come into the picture -- those are or would be good ways to get files/apps onto the device but wouldn't support live debugging. However, adb-over-tcp is an option. I wanted to avoid that for other reasons but they aren't good reasons so that's probably the direction I will go.

[socratis]

OK, thanks for the clarification. Kind of makes sense.

If you ever manage to get adb-over-tcp to work, it wouldn't hurt if you were to post the solution here as well for completion. Some future user might benefit from it...

[michaln]

My hope was that a virtualbox-hosted Android x86 instance would be able to present a USB device port (the same as physical hardware does) such that the virtualbox host or, ideally, another guest would be able to connect to it via adb.

In theory, probably yes. Is anyone bored enough to put a few man-weeks of work into it, probably not.