Re: [libvirt] dpdk/vpp and cross-version migration for vhost

>>>>>>> As version here is an opaque string for libvirt and qemu, >>>>>>> > > > > > >>anything can be used - but I suggest either a list >>>>>>> > > > > > >>of values defining the interface, e.g. >>>>>>> > > > > > >>any_layout=on,max_ring=256 >>>>>>> > > > > > >>or a version including the name and vendor of the backend, >>>>>>> > > > > > >>e.g. "org.dpdk.v4.5.6". >> > > >> > > The version scheme may not be ideal here. Assume a QEMU is supposed >> > > to work with a specific DPDK version, however, user may disable some >> > > newer features through qemu command line, that it also could work with >> > > an elder DPDK version. Using the version scheme will not allow us doing >> > > such migration to an elder DPDK version. The MTU is a lively example >> > > here? (when MTU feature is provided by QEMU but is actually disabled >> > > by user, that it could also work with an elder DPDK without MTU support). >> > > >> > > --yliu > > > > OK, so does a list of values look better to you then? Yes, if there are no better way. And I think it may be better to not list all those features, literally. But instead, using the number should be better, say, features=0xdeadbeef. Listing the feature names means we have to come to an agreement in all components involved here (QEMU, libvirt, DPDK, VPP, and maybe more backends), that we have to use the exact same feature names. Though it may not be a big deal, it lacks some flexibility. A feature bits will not have this issue.