Re: [Qemu-devel] [PATCH 1/3] qdev-ify isa pic

[Gerd Hoffmann <kraxel@redhat.com>]

On 06/10/09 11:43, Filip Navara wrote:
> On Wed, Jun 10, 2009 at 9:32 AM, Gerd Hoffmann<kraxel@redhat.com>  wrote:
> [snip]>
>> In general I think we should handle as much as possible at DeviceState /
>> DeviceInfo level.  Stuff which devices commonly have should live there:
>>   IRQs, mmio, ioports, ... in DeviceState.  name, init and other generic
>> callbacks, ... in DeviceInfo.
>>
>> The bus structs should only hold stuff which is actually specific to that
>> bus.  That is probably almost nothing for sysbus.  i2c has the xfer
>> callbacks in I2CSlaveInfo.  Likewise pci can have the config space
>> read/write callbacks in PCIDeviceInfo.
>
> This is definitely based on wrong assumptions. I've GPIO devices
> modelled on top of qdev and they don't know anything about IRQs, MMIO
> or stuff like that. All they know about is that there are few in/out
> GPIO pins, which are connected to the GPIO controller in the emulated
> microcontroller.

Sure, not every device has IRQs.  Nevertheless almost every bus out 
there supports IRQs.  Thus it is IMHO pointless to have a common thing 
duplicated in each end every bus implementation, it should be in the 
most basic type instead.

That of course doesn't imply that every device must actually use them.

cheers,
   Gerd