Re: [libvirt] [PATCH v2] vl.c: Support multiple CPU ranges on -numa option

Paolo Bonzini <pbonzini(a)redhat.com&gt; writes: There's such thing as list support in QemuOpts. The only way QemuOptsVisitor was able to implement it was to expose QemuOpts publicly via options_int.h and rely on a implementation detail. There are fixed types supported by QemuOpts. It just so happens that whenever qemu_opt_set() is called, instead of replacing the last instance, the value is either prepended or appended in order to implement a replace or set-if-unset behavior. All values are treated this way. So the above "list" would only be: { .name = "cpus", .type = QEMU_OPT_STRING } Which is indistinguishable from a straight string property. This means it's impossible to introspect because the type is context-sensitive. What's more, there is no API outside of QemuOptsVisitor that can actually work with "lists" of QemuOpts values. If we want to have list syntax, we need to introduce first class support for it. Here's a simple example of how to do this. Obviously we would want to introduce some better error checking so we can catch if someone tries to access a list with a non-list accessor. We also would need list accessor functions. But it's really not hard at all. (Only compile tested) Regards, Anthony Liguori