Re: [Xen-devel] PV USB Use Case for Xen 4.x

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Wed, 2012-08-15 at 18:07 +0100, Tom Parker wrote:
> Good Afternoon.  My colleague Stefan (sstan) was asked on the IRC
> channel to provide our use case for PV USB in our environment.  This
> is possible with the current xm stack but not available with the xl
> stack.

Thanks for doing this.

At first glance this doesn't seem like something which we could do for
4.2.0 at this stage, although we should do it for 4.3 and potentially
consider it for 4.2.1.

Is it something which you guys might be interested in providing patches
for? It is at heart a moderately simple C coding exercise, I'm more than
happy to provide guidance etc. Much of the generic framework already
exists and there are examples in the form of other device types.

> Currently we use PVUSB to attach a USB Smartcard reader through our
> dom0 (SLES 11 SP1) running on an HP Blade Server with the Token
> mounted on an internal USB Port to our domU CA server (SLES 11)
> 
> The config file syntax is broken so we have to manually attach (I have
> it scripted) whenever our hosts reboot (which is almost never.)

Can you give an example of what the syntax *should* be?

> On the dom0 server I have to do the following steps:
> 
> /usr/sbin/xm usb-list-assignable-devices (get the bus-id of the USB
> device)
> /usr/sbin/xm usb-hc-create $Domain 2 2 (Create a USB 2.0 Root Hub with
> 2 ports in $Domain)
> /usr/sbin/xm usb-attach $Domain $DevId $PortNumber $BusId (Attach the
> USB bus-id found in step 1 to the hub created in step 2)

What (if anything) is the output of these commands?

Do you need to do anything to make a device "assignable"? (I get no
output from the list command for example)

> On the domU the lsusb looks like this after the above (before it
> returns nothing)
> 
> mgaca:~ # lsusb 
> Bus 001 Device 002: ID 04e6:5116 SCM Microsystems, Inc. SCR331-LC1
> SmartCard Reader
> Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Can you post the output of "xenstore-ls -fp" while the device is
connected?

Do you happen to know if this uses the PVUSB drivers or some other
mechanism? "lsmod" in both dom0 and domU should provide a clue if the
drivers are loaded.

Does this work for both PV and HVM guests or do you only use one or the
other?

> Once I have done this I can use the usb devce in the domU as if it was
> directly connected. 
> 
> Thanks for your time.

Thank you for describing the functionality.

Ian.



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