Re: [Qemu-devel] Why is TYPE_CPU no-user?

[Andreas Färber]

Hi Markus,

Am 15.10.2013 14:24, schrieb Markus Armbruster:
> To go beyond RFC with this series, I need to explain why TYPE_CPU
> cannot_instantiate_with_device_add_yet.  Would you be so kind and help
> me out with a suitable comment?

>From what I remember this was done when I started the whole process and
most CPU subtypes did not yet use the QOM instance_init for
initialization. Most importantly x86 still is not yet self-contained,
nor is sparc. Such targets need to use cpu_init() et al. rather than
-device. (This became visible in the first s390x vCPU hotplug series.)

Most boards rely on being able to do postprocessing after they have
instantiated the CPU: wiring up IRQs, adding reset handlers, halting
non-first CPUs, ...
-device would skip that.

Another aspect is that no CPU subtype has been proven hot-pluggable with
device_add yet. For s390x we're the closest to date.

We could move the flag from the base type to the targets' base types if
you prefer. Then we can knock the bad values out one by one rather than
overriding the inherited value with an explicit positive one.

Cheers,
Andreas

> 
> You can find examples in PATCH 2-7/9.
> 

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