Re: [Qemu-devel] how to handle QOM 'container' objects whose contents depend on QOM properties?

[Paolo Bonzini <pbonzini@redhat.com>]

On 07/02/2018 17:49, Peter Maydell wrote:
>> Yeah, that's why I was wondering if buying an SoC as configurable IP was
>> a thing at all.  In that case, I would just make things less
>> configurable and, if needed, hack the configurability with -global.
>
> So is that a vote for the aspeed style "create N different
> QOM types" ?

Yeah, many types for the SoCs, each setting different properties on the
CPU/nvic/timers/etc.

> It doesn't necessarily help with 'armv7m', which isn't an
> SoC, but just part of the way we currently model M profile CPUs.

Does armv7m have a fixed or variable number of sub-objects?  If it's
fixed, setting up forwarding properties is easy.  But if even parts of
it are variable, it does get messy.

Thanks,

Paolo

> In real hardware, the CPU includes all of the interrupt
> controller, timers, etc, which in QEMU are separate
> objects to the QEMU CPU object and wrapped up inside
> an armv7m container.
> 
> (It would I guess be possible to merge the 'armv7m' container
> entirely into the QEMU CPU object, so creating the CPU object
> gave you an nvic and the mmio register regions to map and so
> on. We don't do anything like that for other cpus right now,
> though...)