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From: Alistair Francis <alistair.francis@xilinx.com>
Date: Wed, 6 Jan 2016 16:18:14 -0800
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Subject: Re: [Qemu-devel] [PATCH v6 1/6] qdev: get_child_bus(): Use QOM
 lookup if available
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To: Peter Crosthwaite <crosthwaitepeter@gmail.com>
Cc: Peter Maydell <peter.maydell@linaro.org>, Peter Crosthwaite <crosthwaite.peter@gmail.com>, "qemu-devel@nongnu.org Developers" <qemu-devel@nongnu.org>, Alistair Francis <alistair.francis@xilinx.com>, qemu-arm <qemu-arm@nongnu.org>, Paolo Bonzini <pbonzini@redhat.com>

On Sat, Dec 19, 2015 at 9:43 PM, Peter Crosthwaite
<crosthwaitepeter@gmail.com> wrote:
> qbus_realize() adds busses as a QOM child of the device in addition to
> adding it to the qdev bus list. Change get_child_bus() to use the QOM
> child if it is available. This takes priority over the bus-list, but
> the child object is checked for type correctness.

This doesn't cause problems for anything else? Is there anything else
with the same name or something where this causes conflicts?

Thanks,

Alistair

>
> This prepares support for aliasing of buses. The use case is SoCs,
> where a SoC container needs to present buses to the board level, but
> the buses are implemented by controller IP we already model as self
> contained qbus-containing devices.
>
> Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
> ---
> Currently qbus_realize() ignores errors from object_property_add_child,
> so it is hard to guarantee that the QOM linkage is reliable. If it were
> the case that that object_property_add_child was supposed to be error
> asserting, we could remove the old bus-list strcmp iterator altogether.
>
>  hw/core/qdev.c | 6 ++++++
>  1 file changed, 6 insertions(+)
>
> diff --git a/hw/core/qdev.c b/hw/core/qdev.c
> index b3ad467..c96c464 100644
> --- a/hw/core/qdev.c
> +++ b/hw/core/qdev.c
> @@ -581,6 +581,12 @@ void qdev_pass_gpios(DeviceState *dev, DeviceState *container,
>  BusState *qdev_get_child_bus(DeviceState *dev, const char *name)
>  {
>      BusState *bus;
> +    Object *child = object_resolve_path_component(OBJECT(dev), name);
> +
> +    bus = (BusState *)object_dynamic_cast(child, TYPE_BUS);
> +    if (bus) {
> +        return bus;
> +    }
>
>      QLIST_FOREACH(bus, &dev->child_bus, sibling) {
>          if (strcmp(name, bus->name) == 0) {
> --
> 1.9.1
>
>