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Date: Thu, 30 May 2013 18:01:55 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/3] pvpanic: use FWCfgState explicitly
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To: Laszlo Ersek <lersek@redhat.com>
Cc: Hu Tao <hutao@cn.fujitsu.com>, qemu-devel@nongnu.org, "Michael S. Tsirkin" <mst@redhat.com>

Il 30/05/2013 18:03, Laszlo Ersek ha scritto:
> On 05/30/13 17:05, Laszlo Ersek wrote:
>> On 05/30/13 15:27, Michael S. Tsirkin wrote:
>>> Use the type-safe FWCfgState structure instead
>>> of the unsafe void *.
>>>
>>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>>> ---
>>>  hw/misc/pvpanic.c | 2 +-
>>>  1 file changed, 1 insertion(+), 1 deletion(-)
>>>
>>> diff --git a/hw/misc/pvpanic.c b/hw/misc/pvpanic.c
>>> index 31e1b1d..1483f27 100644
>>> --- a/hw/misc/pvpanic.c
>>> +++ b/hw/misc/pvpanic.c
>>> @@ -90,7 +90,7 @@ static int pvpanic_isa_initfn(ISADevice *dev)
>>>  {
>>>      PVPanicState *s = ISA_PVPANIC_DEVICE(dev);
>>>      static bool port_configured;
>>> -    void *fw_cfg;
>>> +    FWCfgState *fw_cfg;
>>>  
>>>      memory_region_init_io(&s->io, &pvpanic_ops, s, "pvpanic", 1);
>>>      isa_register_ioport(dev, &s->io, s->ioport);
>>>
>>
>> Doesn't this break your build? Lower down in the function there's
>>
>>         fw_cfg = object_resolve_path("/machine/fw_cfg", NULL);
>>
>> and object_resolve_path() returns a pointer-to-Object, not
>> pointer-to-FWCfgState.
> 
> Paolo explained the guts, but don't we still need a downcast here? (No
> idea how to do that nicely in the object model du jour -- maybe
> OBJECT_CHECK() or similar?)

Patch 2 addresses that.

Paolo