Re: [Qemu-devel] [PATCH for-2.13 2/4] platform-bus-device: use device plug callback instead of machine_done notifier

[Peter Maydell]

On 12 April 2018 at 17:40, Igor Mammedov <address@hidden> wrote:
> platform-bus were using machine_done notifier to get and map
> (assign irq/mmio resources) dynamically added sysbus devices
> after all '-device' options had been processed.
> That however creates non obvious dependencies on ordering of
> machine_done notifiers and requires carefull line juggling
> to keep it working. For example see comment above
> create_platform_bus() and 'straitforward' arm_load_kernel()
> had to converted to machine_done notifier and that lead to
> yet another machine_done notifier to keep it working
> arm_register_platform_bus_fdt_creator().
>
> Instead of hiding resource assignment in platform-bus-device
> to magically initialize sysbus devices, use device plug
> callback and assign resources explicitly at board level
> at the moment each -device option is being processed.
>
> That adds a bunch of machine declaration boiler plate to
> e500plat board, similar to ARM/x86 but gets rid of hidden
> machine_done notifier and would allow to remove the dependent
> notifiers in ARM code simplifying it and making code flow
> easier to follow.
>
> Signed-off-by: Igor Mammedov <address@hidden>

> +static void virt_machine_device_plug_cb(HotplugHandler *hotplug_dev,
> +                                        DeviceState *dev, Error **errp)
> +{
> +    VirtMachineState *vms = VIRT_MACHINE(hotplug_dev);
> +
> +    if (object_dynamic_cast(OBJECT(dev), TYPE_SYS_BUS_DEVICE)) {
> +        if (vms->platform_bus_dev) {
> +            
> platform_bus_link_device(PLATFORM_BUS_DEVICE(vms->platform_bus_dev),
> +                                     SYS_BUS_DEVICE(dev));
> +        }
> +    }
> +}
> +
> +static HotplugHandler *virt_machine_get_hotpug_handler(MachineState *machine,
> +                                                       DeviceState *dev)

Nit: typo in function name, should be "hotplug".

Will let others review the meat of the patch.

thanks
-- PMM