Re: [Qemu-devel] [PATCH v1 1/3] qdev: Expose the qdev id string as a prop

[Peter Crosthwaite]

On Wed, Apr 16, 2014 at 2:16 AM, Andreas Färber <address@hidden> wrote:
> Am 15.04.2014 04:21, schrieb Peter Crosthwaite:
>> So clients can set the top level id string.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>
> Anthony had nack'ed Paolo's attempt to generalize the qdev id to QOM, so
> I'm not sure if we should really do this even if just on device level.
> The id= is used to construct the canonical path, and we can't change
> that through a qdev setter.

How can we change it? The problem I am trying to solve, is getting
meaningful device instance names instead of the anonymous defaults.
This includes in the canonical path. I am completely open to proposals
:)

 Using a dynamic property might allow us to
> unparent while keeping a reference and then add it as a child<> again,
> but that still feels awkward.

Eww.

 Having it as a getter only seem more
> secure and predictable.
>

Sure, once it's committed to the canonical path it definitely needs a
read-only semantic. Shouldn't be hugely different to the
writable-until-realize semantic of qdev props though?

> Another issue is bus naming. If supplied NULL, the bus will be based on
> ID. If the ID changes, bus naming will be inconsistent.
>

Or rather - what the user intends. If the board has 2 USB busses named
"foo" and "bar", then those should be both the canonical path and bus
names. Rather than the homogenised default names "usb0", "usb1".

> Why would clients set the ID after having chosen a different ID

I'm lost here - what is the mechanism by which you can validly set
per-instance IDs?

Regards,
Peter

or
> anonymity?
>
> Regards,
> Andreas
>
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