Re: [Qemu-devel] Hi Natalia.. A query regarding QEMU

Re: [Qemu-devel] Hi Natalia.. A query regarding QEMU

[Natalia Portillo]

Hi Ankit,

El 03/11/2011, a las 20:37, Ankit Verma escribió:

> Hi Natalia,
> 
> I am trying to support usb connections on Android Emulator. Since
> Android Emulator is based on QEMU, i thought you could give some
> insight on how to enable usb connections for android emulator.
> 
> As per the following information in google's android website -
> http://developer.android.com/guide/developing/devices/emulator.html
> 
> Emulator Limitations
> 
> In this release, the limitations of the emulator include:
> 
>>>> No support for USB connections
> No support for Bluetooth
> 
> Can you give some insight.

First of all, while Android Emulator is based on QEMU, they have made their own modifications, that have not been sent to us, so it's not 100% QEMU.

What I can tell you is that Android phones/tablets are USB devices, and QEMU have an incomplete support for REAL USB devices with QEMU behaving as an USB host. But QEMU is not designed currently to work as a USB device to a real USB host.

If you want to code that support yourself, you'll need a virtual host controller implementation on the host operating system, and then implementing QEMU behavior as an Android device (be it USB Mass Storage Device or Android Debug device).

For the first part, there are some implementations, called USB-IP, that create a virtual host controller both on Windows and on Linux hosts, and both are incomplete as I write.
For the second part that has never been tried (afaik) and would be mostly dependent on what solution you chose for the first part (as there will never be a way for QEMU to talk to a real host controller as a device).

I hope this gives insight for you, and any other question I may be of help, feel free to ask.

BTW, I'm CCing this to the mailing list, as other people may find this interesting, want to contribute with their opinions, so on.

Regards,
Natalia Portillo

Re: [Qemu-devel] Hi Natalia.. A query regarding QEMU

[Gerd Hoffmann]

  Hi,

> What I can tell you is that Android phones/tablets are USB devices,
> and QEMU have an incomplete support for REAL USB devices with QEMU
> behaving as an USB host. But QEMU is not designed currently to work
> as a USB device to a real USB host.
> 
> If you want to code that support yourself, you'll need a virtual host
> controller implementation on the host operating system, and then
> implementing QEMU behavior as an Android device (be it USB Mass
> Storage Device or Android Debug device).

Another option would be to explore the usbredir support recently added
to qemu.  The focus of the current implementation is to support
forwarding usb devices over the network.  You have a little server
running which export a usb device, and qemu's usbredir backend connects
to the server and allows the guest to access the device.

Of course you can replace the server side with something emulating a usb
device, for example a emulated android device with usb-host support,
i.e. you have two qemu's running, one with android, one with a linux or
windows guest os, and you'll link the two using the usbredir protocol.

Cc'ing Hans who wrote the usbredir support.

cheers,
  Gerd