Re: [Qemu-devel] [PATCH v1 3/4] hw: Deduce the default machine from the specified CPU model

[Peter Maydell]

On 27 August 2012 21:37, Meador Inge <address@hidden> wrote:
> This changes the driver behavior to choose the default machine
> model based on the CPU being used.  Defaulting the machine this
> way makes it easier to use QEMU as an ISS by just specifying
> the -cpu option since a default machine that is suitable for
> emulating the full ISA can be chosen.
>
> For example, currently on ARM the ARM Integrator/CP board is
> chosen as the default machine when specifying just a CPU.
> However, this doesn't work well when passing -cpu cortex-m3
> since on ARMv7-M processors the NVIC is a part of the architecture
> and is needed to support instructions like SVC.

Personally I'd rather we didn't support a "default machine" at
all, at least for ARM. It does matter what board you run on,
so you need to specify.

Just to pick an obvious example, you can't stick a core
which supports VFPv4 (the A15 is the only one we have) into
the integratorcp, so you would still have to specify both
a CPU and a machine name there.

We could reasonably add patches which made boards error
out if you tried to use them with unsupported CPUs, I guess.

-- PMM