Re: [Qemu-devel] [PATCH] qdev: Keep global allocation counter per bus

[Markus Armbruster]

Alexander Graf <address@hidden> writes:

> When we have 2 separate qdev devices that both create a qbus of the
> same type without specifying a bus name or device name, we end up
> with two buses of the same name, such as ide.0 on the Mac machines:
>
>   dev: macio-ide, id ""
>     bus: ide.0
>       type IDE
>   dev: macio-ide, id ""
>     bus: ide.0
>       type IDE
>
> If we now spawn a device that connects to a ide.0 the last created
> bus gets the device, with the first created bus inaccessible to the
> command line.
>
> After some discussion on IRC we concluded that the best quick fix way
> forward for this is to make automated bus-class type based allocation
> count a global counter. That's what this patch implements. With this
> we instead get
>
>   dev: macio-ide, id ""
>     bus: ide.1
>       type IDE
>   dev: macio-ide, id ""
>     bus: ide.0
>       type IDE
>
> on the example mentioned above.

What I don't like about the global counter: we define the board's ABI
implicitly by device initialization order.  Bad taste and fragile, but
we do this elsewhere, too, e.g. pci_create_simple(bugs, -1, ...).

Wanted: tests to catch accidental ABI changes, covering at least the
parts we define implicitly.