Re: [Qemu-devel] Re: [PATCH v2 9/9] Add -kvm option

[Anthony Liguori <aliguori@us.ibm.com>]

Gerd Hoffmann wrote:
> On 10/12/09 16:04, Anthony Liguori wrote:
>> Gerd Hoffmann wrote:
>>> -M $machine gives you a barebone machine with all core devices which
>>> belong to it. You can't easily remove and/or replace devices.
>>> Especially not something central as the IRQ controller. But also no
>>> other core components, i.e. you wouldn't stick a piix4 ide controller
>>> into a Q35 machine. Just say 'no'.
>>
>> This seems fundamentally flawed to me. If you cannot remove a device
>> from a machine using command line options, then how do we support
>> something like -net none?
>
> '-net none' does not remove a nic.  It makes qemu not add the default 
> nic.

qemu should not have the concept of a default nic.   Instead, if you 
choose the pc machine type, by default you get an e1000.  I think it's 
also reasonable to get a USB controller too along with the balloon 
driver and anything else we think a user could benefit from.

If you give devices well known ids, then changing a default device is 
not really that big of a deal.  It involves removing the device and 
adding a new device with that same device id.

For platform devices, like the interrupt controller/pic, the same 
principle could be applied to switch out a userspace irqchip/pit with 
the kvm kernel implementations.

-- 
Regards,

Anthony Liguori