Re: [Qemu-devel] [SeaBIOS] [PATCH] don't expose pvpanic device in the UI

["Andreas Färber" <afaerber@suse.de>]

Am 06.08.2013 10:36, schrieb Gleb Natapov:
> On Tue, Aug 06, 2013 at 11:33:10AM +0300, Michael S. Tsirkin wrote:
>> On Tue, Aug 06, 2013 at 10:21:52AM +0300, Gleb Natapov wrote:
>>>> If you see a mouse in a room, how likely is it that there's
>>>> a single mouse there?
>>>>
>>>> This is a PV technology which to me looks like it was
>>>> rushed through and not only set on by default, but
>>>> without a way to disable it - apparently on the assumption
>>>> there's 0 chance it can cause any damage. Now that
>>>> we do know the chance it's not there, why not go back
>>>> to the standard interface, and why not give
>>>> users a chance to enable/disable it?
>>> You should be able to disable it with: -device pvpanic,ioport=0
>>
>> Doesn't work for me.
> Bug that should be fixed. With this command line _STA should return
> zero.
> 
>> Besides, both -device pvpanic and use of ioport=0 to disable it
>> are completely undocumented.
>>
> Not the only undocumented thing in QEMU command line :)
[snip]

I disagree: -device adds a device, not removes one. It will still be
present.

I am neutral as to whether qemu-system-x86_64 should have it enabled by
default or not. But if we want to suppress it, then -nodefaults should
disable it. Since libvirt uses that though, it would mean libvirt would
need to add it back, whether via user's XML domain config or by libvirt
itself based on some version/etc. heuristics.

Andreas

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