Re: [libvirt] [Xen-devel] [PATCH] libxl: allow an <emulator> to be selected in the domain config XML

On 31.05.2013 10:25, Ian Campbell wrote: > On Thu, 2013-05-30 at 11:53 -0600, Jim Fehlig wrote: >> Marek Marczykowski wrote: >>> On 01.05.2013 16:11, Daniel P. Berrange wrote: >>> >>>> On Wed, May 01, 2013 at 02:44:11PM +0100, David Scott wrote: >>>> >>>>> On 01/05/13 09:46, Ian Campbell wrote: >>>>> >>>>>> I would suggest that libvirt+libxl expose the version as the "emulator" >>>>>> option and not the path. Just leave the path as the default in the >>>>>> normal case. You may also want to provide an extra >>>>>> emulator-path-override tag/attribute/XML for advanced users, but that's >>>>>> up to you. >>>>>> >>>>>> If you need to support upgrade from xend then you could perhaps treat >>>>>> <emulator> values not in the set of valid LIBXL_DEVICE_MODEL_VERSION >>>>>> string (currently "qemu-xen" and "qemu-xen-traditional") as a path to a >>>>>> qemu-xen-traditional device model -- no xend user can possibly have been >>>>>> using the new device model with xend. Or you could take the approach >>>>>> that xl does and just warn. >>>>>> >>>>> This would work for me: it doesn't seem too bad to consider >>>>> "qemu-xen" and "qemu-xen-traditional" as special virtual paths. It's >>>>> a useful observation that xend never supported the new device model. >>>>> Jim: should I cook up patch v3? :-) >>>>> >>>> No, that really doesn't fly. The <emlator> element must always point >>>> to a qualfied binary path. >>>> >>>> IMHO, libvirt should just default to the new QEMU binary and if people >>>> want to use the old one, they can configure the emulator path for it. >>>> >>> >>> What about stubdom? Any idea how to do it better than special paths? Even if >>> given path will point to stubdom binary, I don't know how libvirt shoud >>> distinguish it from standalone qemu and set b_info->device_model_stubdomain >>> accordingly. >>> >> >> As mentioned in my reply to your stubdom patch, this should be handled >> in libxl IMO. > > The default is handled in libxl, so you don't need to do anything if you > don't want to. It's up to you if you want to provide an override > facility in libvirt. Personally I'd do it with a specific XML > property/key/whatever rather than magic emulator paths... Optional attribute for <emulator> tag? Maybe sth like: <emulator type="stubdom">/usr/lib/xen/boot/ioemu-stubdom.gz</emulator> ?