[Qemu-devel] '.' IDs and certain names breaks -global and -set

[Markus Armbruster]

We have a number of device model names containing '.'.  They're unusable
with -global.  That's because "-global A.B.C=foo" gets parsed as

    driver = "A"
    property = "B.C"
    value = "foo".

Wrong when the device model name is really A.B and the property is C,
e.g. "-global cfi.pflash01.name".

Related problem: QemuOpts ID may contain '.'.  Such IDs are in fact
common practice.  Unfortunately, they're unusable with -set.  For
instance, -set A.B.C.D=foo gets parsed as

    group = "A"
    id = "B"
    arg = "C.D"
    value = "foo"

Wrong when the id is really B.C and the arg is D, e.g. "-device
isa-serial,id=s.0 -set device.s.0.chardev=c0".  This issue isn't limited
to devices.

Related historical problem: commit b560a9a.

Possible solutions:

* Outlaw '.' in QemuOpts parameter names (and thus device model names
  and property names, because QemuOpts is a major way for users to
  specify them).

* Resolve the syntactic ambiguity semantically (ugh)

* Extend the syntax of -global and -set to let users avoid the issue, or
  replace them outright

* Use the old ostrich algorithm

Andreas, what restrictions does QOM place on QOM path component names?
No '/', obviously.  Anything else?