Re: [Xen-devel] Deprecated option -usbdevice in QEMU

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Mar 14, 2018 at 02:29:17PM +0000, Anthony PERARD wrote:
> Hi,
> 
> In an xl guest config, we have the "usbdevice" option. It is just
> passthrough to QEMU "-usbdevice" without parsing. The QEMU option is now
> deprecated. v2.11 (to be released with Xen 4.11) is the last version of
> QEMU to have the option.
> 
> Unfortunatly, our documentation relie on QEMU's documentation, so there
> would be a lot to parse if we want to keep the option.
> 
> I propose that we also deprecated the "usbdevice" option and find a
> suitable alternative (or we have to parse usbdevice in libxl).

If we want to be backward compatible we need to parse the string anyway,
regardless of whatever new thing we recommend, right?

> 
> "usbdev" seems to be a good fit for that, and should already handle
> "usbdevice='host:bus.addr', but would be written:
> "usbdev=['type=hostdev,hostbus=bus,hostaddr=addr']"
> 
> The other use of "usbdevice" documented on the man are:
> - tablet
> - host:vendor_id:product_id
> 
> Other usage of "usbdevice" documented in the QEMU documentation:
> - mouse
> - disk:[format=format]:file
> - serial:[vendorid=vendor_id][,productid=product_id]:dev
> - braille
> - net:options
> 
> 
> From QEMU perspective, those options can be replaced the following
> cmdline options or QMP command equivalent (I haven't check everything):
> * -device usb-tablet
> * -device usb-host,vendorid=vendor,productid=product
> * -device usb-mouse
> * -drive if=none,id=drive_id,file=file  -device usb-storage,drive=drive_id
> * -chardev x,id=id -device usb-serial,chardev=id
> * -device usb-braille
> * -netdev x,id=id -device usb-net,netdev=id
> 
> 
> How the original "usbdevice" could be translated into a USBDEV_SPEC for
> "usbdev" ? Maybe for e.g.:
> 'type=tablet'
> 'type=storage,file=file,format=format'
> 
> I don't know is anybody would be using "usbdevice='net:...'" or
> "usbdevice='serial:...'".
> 
> What do you think?

I would be fine with restricting usage to a few known devices and reject
the rest. There is already a kitchen sink device_model_args that we can
turn to.

Wei.


> 
> Thanks,
> 
> -- 
> Anthony PERARD

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