Re: [PATCH v5 1/1] util/async-teardown: wire up query-command-line-options

From: Thomas Huth <thuth@redhat.com>
To: Markus Armbruster <armbru@redhat.com>,
	Paolo Bonzini <pbonzini@redhat.com>
Cc: "Claudio Imbrenda" <imbrenda@linux.ibm.com>,
	qemu-devel <qemu-devel@nongnu.org>,
	"David Hildenbrand" <david@redhat.com>,
	"Borntraeger, Christian" <borntraeger@de.ibm.com>,
	"Janosch Frank" <frankja@linux.ibm.com>,
	fiuczy@linux.ibm.com, "Halil Pasic" <pasic@linux.ibm.com>,
	nsg@linux.ibm.com, "P. Berrange, Daniel" <berrange@redhat.com>,
	"Alex Bennée" <alex.bennee@linaro.org>
Subject: Re: [PATCH v5 1/1] util/async-teardown: wire up query-command-line-options
Date: Tue, 28 Mar 2023 09:20:06 +0200	[thread overview]
Message-ID: <98a65e35-9c56-df86-66ed-f949c1fb9c96@redhat.com> (raw)
In-Reply-To: <87cz4t5tuo.fsf@pond.sub.org>

On 28/03/2023 07.26, Markus Armbruster wrote:
> Paolo Bonzini <pbonzini@redhat.com> writes:
> 
>> I am honestly not a fan of adding a more complex option,.just because
>> query-command-line-options only returns the square holes whereas here we
>> got a round one.
>>
>> Can we imagine another functionality that would be added to -teardown? If
>> not, it's not a good design. If it works, I would add a completely dummy
>> (no suboptions) group "async-teardown" and not modify the parsing at all.
> 
> Does v2 implement your suggestion?
> Message-Id: <20230320131648.61728-1-imbrenda@linux.ibm.com>
> 
> I dislike it, because it makes query-command-line-options claim
> -async-teardown has an option argument with unknown keys, which is
> plainly wrong, and must be treated as a special case.  Worse, a new kind
> of special case.

I agree with Markus, it sounds like a bad idea to create a new special case 
for this.

Paolo, what do you think of my "-run-with" suggestion here:

https://lore.kernel.org/qemu-devel/3237c289-b8c2-6ea2-8bfb-7eeed637efc7@redhat.com/

I still think that this is a good idea, even if it is a "grab-bag" as Markus 
said, it would give us a place where we could wire future similar options, 
too, without running into this problem here again and again.

> Can we have a QMP command, so libvirt can use query-qmp-schema?

Question is whether this could be toggled during runtime...? Or did you mean 
a command that just queries the setting of the option, e.g. 
"query-async-teardown" which then reports whether it is enabled or not?

> In case QMP becomes functional too late for the command to actually
> work: make it always fail for now.  It can still serve as a witness for
> -async-teardown.  If we rework QEMU startup so that QMP can do
> everything the CLI can do, we'll make the QMP command work.

Adding non-working functions sounds ugly... Anyway, we're slowly running out 
of time for QEMU 8.0 ... if we can't find an easy solution, I think we 
should rather postpone this to the next cycle instead of rushing unfinished 
stuff now.

  Thomas