Re: [Qemu-devel] [patch 2/6] Use machine options to emulate -no-kvm-irqchip

Anthony Liguori
2012-10-04T14:21:33Z

Jan Kiszka <jan.kiszka@web.de> writes:

> On 2012-10-03 20:26, Marcelo Tosatti wrote:
>> On Wed, Oct 03, 2012 at 07:24:48PM +0200, Jan Kiszka wrote:
>>> On 2012-10-03 19:16, Anthony Liguori wrote:
>>>> Jan Kiszka <jan.kiszka@web.de> writes:
>>>>
>>>>> On 2012-10-03 17:03, Marcelo Tosatti wrote:
>>>>>> On Wed, Oct 03, 2012 at 09:40:17AM -0500, Anthony Liguori wrote:
>>>>>>> Marcelo Tosatti <mtosatti@redhat.com> writes:
>>>>>>>
>>>>>>>> Commit 3ad763fcba5bd0ec5a79d4a9b6baeef119dd4a3d from qemu-kvm.git.
>>>>>>>>
>>>>>>>> From: Jan Kiszka <jan.kiszka@siemens.com>
>>>>>>>>
>>>>>>>> Upstream is moving towards this mechanism, so start using it in qemu-kvm
>>>>>>>> already to configure the specific defaults: kvm enabled on, just like
>>>>>>>> in-kernel irqchips.
>>>>>>>>
>>>>>>>> Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>
>>>>>>>
>>>>>>>
>>>>>>> Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>
>>>>>>>
>>>>>>> Although it's a little odd to have From: Jan without a SoB...
>>>>>>
>>>>>> Agree, Jan can you ACK?
>>>>>
>>>>> I wasn't able to join the call yesterday: Is there a removal schedule
>>>>> associated with those switches? Also, why pushing things upstream, even
>>>>> when only for one release, that have been loudly deprecated for a while
>>>>> in qemu-kvm? Some switches are lacking deprecated warnings on the
>>>>> console, and -no-kvm is missing completely. I tend to focus on patch 1 &
>>>>> 5, dropping the rest - based on relevance for production use.
>>>>
>>>> The distros need to keep these flags to do the switch.
>>>
>>> Why? Should be documented in commit log.
>>>
>>>> I see no point
>>>> in deprecating them since they're trivially easy to maintain.
>>>
>>> Given the level of cr** we already have in the command line, they are
>>> kind of noise, yes. But even then, these patches are not consistent as
>>> pointed out above.
>>>
>>> Also, they should not be documented to avoid being spread. That's what
>>> we did with other deprecated switches in QEMU.
>>>
>>> Jan
>>
>> Jan,
>>
>> You're comments to the patch are:
>>
>> - No documentation.
>
> See e.g. how -M is handled in qemu-options.hx.
>
>> - Expiration date.
>
> Anthony said "forever", but I think we should remove all those that
> issue deprecation warnings after 1-2 years.
>
>> - Changelog explaining what?? (didnt get that). Perhaps better changelog
>> in general?
>
> I'm still failing to understand who could depend on -no-kvm-irqchip or
> -no-kvm-pit. And I don't understand why -no-kvm was not included. Soe
> the reasons for include -X should be provided. Also check your patch
> subjects again, at least one was wrong.

-no-kvm should be included too.

I just ran across a user that was injecting '-no-kvm-irqchip' in their
libvirt XML via a custom attribute. It turned out it was to work around
broken MSI support in their funky guest they were running. It was the
wrong solution to the problem but they were doing it regardless.

The point is, there are users in the wild using these options. There's
no reason to remove them if they are trivial to maintain (and they are
in their current form).

Regards,

Anthony Liguori

>
> Jan