Am 30.09.2016 um 16:45 hat Daniel P. Berrange geschrieben: > Some of the historical command line opts that had their > keys in in a completely flat namespace are now represented > by QAPI schemas that use a nested structs. When converting > the QemuOpts to QObject, there is no information about > compound types available, so the QObject will be completely > flat, even after the qdict_crumple() call. So when starting > a struct, we may not have a QDict available in the input > data, so we auto-create a QDict containing all the currently > unvisited input data keys. Not all historical command line > opts require this, so the behaviour is opt-in, by specifying > how many levels of structs are permitted to be auto-created. > > Note that this only works if the child struct is the last > field to the visited in the parent struct. This is always > the case for currently existing legacy command line options. > > The example is the NetLegacy type which has 3 levels of > structs. The modern way to represent this in QemuOpts would > be the dot-separated component approach > > -net vlan=1,id=foo,name=bar,opts.type=tap,\ > opts.data.fd=3,opts.data.script=ifup > > The legacy syntax will just be presenting > > -net vlan=1,id=foo,name=bar,type=tap,fd=3,script=ifup > > So we need to auto-create 3 levels of struct when visiting. > > The implementation here will enable visiting in both the > modern and legacy syntax, compared to OptsVisitor which > only allows the legacy syntax.
So you're actually introducing the modern syntax only now? I don't think an "opts.data." prefix makes a lot of sense. I suspect the schema looks this way only because we didn't have flat unions in 1.2. So, considering that it is a purely internally used type not visible in QMP, would it make sense to change NetLegacy to be a flat union instead, with NetLegacyOptions as the common base? Then you get the same flat namespace that we always had and that makes much more sense as an API. Kevin
