Re: [RFC PATCH 2/2] hw/arm/raspi: Restrict BCM2835 / BCM2836 SoC to TCG

[Paolo Bonzini]

On 01/02/21 09:46, Philippe Mathieu-Daudé wrote:
> > > +#ifdef CONFIG_TCG
> > I'm not sure it's enough. TCG and KVM can be enabled in the same
> > binary. You'll have to perform a runtime check here I think.
> If TCG is enabled, all SoC are built in (regardless of KVM enabled).
> If only KVM is enabled, the TCG part is not built in (only ARMv8
> based SoC left).
>
> The problem is when QOM types are registered, we can not know
> yet if the accelerator is enabled, because accelerators are also
> QOM types and are realized later. So at this point runtime check
> is not possible. See this post:
> https://www.mail-archive.com/qemu-devel@nongnu.org/msg777761.html

The check should be done on the CPU type, not on the accelerator.

On top of that you could add a "depends on TCG" to the hw/arm/Kconfig 
file, but Luc is correct that it would be just a nice-to-have and not 
the real fix.

Paolo