Re: [Qemu-devel] Re: [PATCH] Add -no-virtio-balloon command-line option

[Anthony Liguori <anthony@codemonkey.ws>]

Dor Laor wrote:
> Anthony Liguori wrote:
>> Markus Armbruster wrote:
>>> Dor Laor <dlaor@redhat.com> writes:
>>>
>>>  
>>>> Gerd Hoffmann wrote:
>>>>   
>>>>>> This new option may be used to disable the virtio-balloon device.
>>>>>>
>>>>>>         
>>>>> ACK, looks good.
>>>>>
>>>>> And I can drop my lazy patch which just comments out virtio-balloon
>>>>> in the code ;)
>>>>>       
>>>> Actually, I rather have the balloon disabled by default. It's like any
>>>> other pci device which needs
>>>> explicit command line specification. Why consume a pci slot if not
>>>> implicitly required?
>>>>     
>>>
>>> I agree.  The command line is plenty magic without implicitly added
>>> PCI devices.
>>>
>>> Besides, negative options -no-virtio-balloon lead to ugly
>>> double-negatives like if (!no_virtio_balloon).
>>>   
>>
>> It does no harm to add the device by default so why force the user to 
>> explicitly enable it?
>
> It consumes one of the 32 pci devices we have today. It's the same for 
> not having -usb as default
> or any other type of device. Soon we'll need pci_addr= along with it 
> anyway ;)

IMHO, -usb should be default.  It wasn't made default when it was 
introduced because it was known to be buggy.

For management tools, explicitly disabling something is easy enough.  
For humans, I think wanting features is more common than needing more 
than 32 PCI slots.

Regards,

Anthony Liguori

> Dor
>