On 5/8/2026 9:10 AM, Daniel P. Berrangé wrote:
> On Tue, May 05, 2026 at 03:48:20PM -0700, Pierrick Bouvier wrote:
>> We are getting close to be able to link several targets in a single QEMU 
>> system
>> binary, and the last obstacle on the road is to embed several TargetInfo in 
>> the
>> same binary. The end result of this series is to have a single definition for
>> target_info symbol.
>>
>> This series adds TargetInfo types in QOM, and retrieve them dynamically(). At
>> the moment, we don't deal yet with multiple TargetInfo selection, but install
>> all that is needed to be able to do it easily.
>>
>> Because TargetInfo data is set through class_init, it creates an issue at
>> startup, where we may try to instantiate additional (unrelated) types just to
>> retrieve the list of "target-info-X" types. Those other types class_init may 
>> be
>> using target information, to add target specific properties for instance.
>> This issue has been fixed by adding a new 
>> object_class_get_list_by_name_prefix
>> that does not force instantiation of all QOM types, but only those matching a
>> specific pattern. This way, we first initialize and retrieve target-info 
>> types
>> before others.
>>
>> An alternative would be to leave all this out of QOM, and use startup
>> initializer to add them in a single list. However, because all the 
>> single-binary
>> work has been using QOM where possible, it would be really sad to not use it 
>> for
>> this final step. Comments are welcome!
>>
>> Finally, sticking to our promise not create a special "single-binary
>> configuration", the goal is to use the *exact* same codepath for normal 
>> binaries
>> also. It means that even for existing system binaries, the goal will be to 
>> use
>> QOM to retrieve current target, even if there is only one.
>>
>> v4
>> --
>>
>> - Revert to v2 MODULE_INIT_TARGET_INFO as Daniel didn't comment on issues 
>> about
>>   about MODULE_INIT_QOM_EARLY.
> 
> Sorry for  not responding to that, other things got in the way
> this week.
>

No worries, that's a good lesson for me about not interpreting not
having answer as a lack of interest when someone is active on other threads.

> For clarity, I withdraw my objections from v2. Having seen how
> my suggested approadch in v3 looked, I think you were correct
> all along.
>

The important is that we explored this path and its limitations.

> With regards,
> Daniel

Thanks Daniel,
Pierrick

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