[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 3/3] libxl: add new pvusb backend "qusb" provided by qemu
On 29/03/16 11:45, George Dunlap wrote: > On Fri, Mar 25, 2016 at 6:09 AM, Juergen Gross <jgross@xxxxxxxx> wrote: >> On 24/03/16 21:07, Wei Liu wrote: >>> On Fri, Mar 18, 2016 at 09:24:26AM +0100, Juergen Gross wrote: >>>> On 17/03/16 17:55, George Dunlap wrote: >>>>> On Thu, Mar 10, 2016 at 3:00 PM, Juergen Gross <jgross@xxxxxxxx> wrote: >>>>>> Add a new pvusb backend type "qusb" which is provided by qemu. It can >>>>>> be selected either by specifying the type directly in the configuration >>>>>> or it is selected automatically by libxl in case there is no "usbback" >>>>>> driver loaded. >>>>>> >>>>>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> >>>>> >>>>> Oh, last thing -- shouldn't we have a way for libxl to tell whether >>>>> qemu can provide a qusb backend before we offer to start it up? >>>> >>>> How? Is this possible for qdisk? Or for an emulated frame buffer? >>>> >>> >>> I don't think it is possible at the moment. But I think you might be >>> able to do it either via qmp command or parsing qemu help string. The >>> latter functionality is implemented in Ian's device model deprivilege >>> patch series IIRC -- but it is not yet merged either. >> >> Won't help for qusb, as there is no qemu parameter or help text related >> to the backend. It would be possible to add a qmp command to print the >> supported backend types, of course. > > Well as I understand it, for qemu-upstream we can't assume what > version of qemu we'll end up getting: we need to be compatible with > recent releases of qemu which don't provide qusb. Which I'm pretty > sure means failing gracefully (i.e., giving a sensible warning > message) if someone tries to add qusb when their qemu binary doesn't > support it. > > If you can tell from the qemu failure that qusb is at fault, that's OK > I think; but if not, I think you'll have to add some way to query > whether qusb is supported by the qemu binary before starting it. So we would want a qemu command line option (e.g. -xen-help) printing the supported pv backends. I think this should be easy to setup. Juergen _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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