Re: [Qemu-devel] [PATCH for-1.6] pc: fix up pc initialization

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

Andreas Färber <afaerber@suse.de> writes:

> Am 13.08.2013 17:27, schrieb Paolo Bonzini:
>> Il 13/08/2013 17:11, Andreas Färber ha scritto:
>>>
>>> mst suggested to patch stable-1.5 to disable it there, too. I am not
>>> against but have doubts as to how well that works with migration, since
>>> 1.5.3 is still a bit off and I would expect 1.5.2 -> 1.6.0 migration to
>>> work without guest-visible changes... We could argue that having to use
>>> -M pc-i440fx-1.5 we can also expect users to add -device pvpanic;
>>> question would be how to convey that knowledge of
>>> if-you-use-pc-x.y-then-you-also-need-to-do-Z to users, which
>>> compat_props usually handle under the hood. We could misuse
>>> pvpanic.ioport=0 for that purpose until we have a better solution.
>> 
>> pvpanic has no vmstate though, has it?  So it won't break migration
>> (needs testing of course).
>
> Just checked, you're right, it doesn't. I somehow assumed it would.
>
>> All that should happen is that after migration you will not get panic
>> notifications on the destination.
>
> Well, how does the Linux driver cope with pvpanic device present on boot
> but not present on panic? ISA PIO is not usually expected to be
> hot-unplugged. ;)

Yeah, disappearing doesn't seem acceptable to me.

We made a mistake with 1.5, now we have to live with it.

Regards,

Anthony Liguori

>
> Andreas
>
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