[pve-devel] [PATCH qemu-server 2/8] config to command: add one '-global' option for each flag

[Dominik Csapak]

On 3/7/25 11:00, Fiona Ebner wrote:
> Am 07.03.25 um 10:54 schrieb Dominik Csapak:
>> On 3/6/25 13:55, Fiona Ebner wrote:
>>> Am 06.03.25 um 13:15 schrieb Dominik Csapak:
>>>> On 3/6/25 13:13, Fiona Ebner wrote:
>>>>> Am 06.03.25 um 11:44 schrieb Dominik Csapak:
>>>>>> If we have multiple 'globalFlags', we have to encode each one
>>>>>> separately
>>>>>> on the commandline with '-global OPTION', since QEMU does not allow to
>>>>>> have multiple options here.
>>>>>>
>>>>>> We currently only have one such flag that used the 'globalFlags' list,
>>>>>> so it never popped up. (All other uses directly add an option to the
>>>>>> commandline)
>>>>>>
>>>>>> Avoid future bugs by fixing it now.
>>>>>>
>>>>>
>>>>> So there is no real point to collecting the flags in the first place?
>>>>> I.e. we could also get rid of the variable and have the single current
>>>>> user of the variable add the flag directly on the commandline too. Or
>>>>> otherwise, we could change the other users and collect all flags with
>>>>> this variable. Pre-existing of course, but ideally, we could avoid the
>>>>> mishmash.
>>>>>
>>>>
>>>> Sorry this could have been more clear here:
>>>> I add to the flags in one of the following patches, so i sent this
>>>> in preparation of that (could possibly be squashed)
>>>
>>> Yes, I understand that. I still think the status quo with mixing two
>>> different approaches might not be best. It's not going to be a blocker
>>> for the series, but I wanted to mention it, if you want to go for
>>> avoiding it.
>>>
>>>> I did not want to touch the other places, since that in turn changes
>>>> the order of the qemu commandline (which sometimes has unintended side
>>>> effects, e.g. in combination with the 'args' parameter)
>>>
>>> Are you sure? Custom 'args' are always added last so that shouldn't
>>> matter.
>>>
>>> The only thing that would change by removing the global flags variable
>>> is having "-global kvm-pit.lost_tick_policy=discard" earlier in the
>>> commandline. I think that should be fine. In particular QEMU's
>>> qemu_init() function has a call to user_register_global_props() which
>>> handles all global properties at the same time, so I think changing the
>>> order should be fine in (almost?) all cases.
>>
>> I'll test that, but imho it would better to do the reverse here?
>> So don't interject '-gloabl' parameters throughout config2command, but
>> add them to the globalFlags and output them together at the end?
>>
>> we'd have to touch the same number of tests i think, but it seems less
>> confusing to me (also in the resulting commandline we'd have all
>> global options together then)
>>
>> Or is there a better argument for injecting the global parameters
>> in the middle?
> 
> It avoids the need for the variable to collect and passing it around and
> to remember adding future ones to that variable too.
> 
> It doesn't make a difference from QEMUs perspective, but would slightly
> improve readability for humans looking at the commandline.
> 
> Note that I already suggested collecting all in the variable as an
> approach above. I just want to avoid the mishmash.

OK, which approach would you prefer? (I don't have a strong feeling in either direction
and doing the cleanup now seems to not be a lot of work)